Code P0507: diagnosis, causes, and solutions

P0507 – idle speed higher than normal. The engine control module registers this code when the actual idle speed consistently exceeds the target range (usually 600–900 rpm for gasoline engines). A common threshold for GM systems is an excess of 200 rpm. Main causes include air leaks, throttle body or idle air control (IAC) valve contamination, faulty positive crankcase ventilation (PCV) valve, and less commonly, issues with the evaporative purge valve (EVAP). Diagnosis starts with leak detection (smoke machine, spray test), cleaning the throttle body and IAC followed by relearn. Driving is possible with caution over short distances, but if idle speed exceeds 1500 rpm or frequent stalling occurs, it is advisable to stop—the braking distance increases, transmission wear accelerates, and there is a risk of catalytic converter overheating.

“When I see P0507, the first thing I check is not the IAC valve, but the conditions under which the PCM cannot close the airflow. The code indicates a symptom, not the root cause—and that’s the key difference. Look for the source of excess air before replacing components.” – Daniel Brooks, DecodeAuto

Error P0507: what the code means and why idle speed is too high

DTC P0507 stands for Idle Air Control System RPM Higher Than Expected—the idle control system detects engine speed above the expected level. When the PCM observes a stable idle speed increase after engine warm-up (usually within 10–15 minutes of operation), it stores the code and triggers the Check Engine light.

Conditions for code setting:

• Measured idle speed exceeds the target range (for most gasoline engines, this is 600–900 rpm).
• The excess is ≥200 rpm for some GM systems.
• The PCM attempts to adjust airflow via the throttle or IAC valve but cannot compensate for the leak.

The code may result from mechanical causes (air leaks, throttle contamination, IAC sticking) or electrical issues (sensor faults, wiring problems, PCM adaptations). In any case, the PCM detects a mismatch between the command to close airflow and the engine’s actual behavior.

This information is general and does not replace professional consultation.

The code complies with OBD-II standards: SAE J1979 (diagnostic methods, data formats). ISO 15031-5:2011 is technically equivalent to SAE J1979:2010 and regulates diagnostic services, while specific code definitions are in SAE J2012-DA.

Symptoms of P0507 malfunction

Main symptoms and manifestations of code P0507

Key indicators pointing to P0507:

• Elevated idle speed—rpm held at 1100–1500 instead of the normal 600–900 rpm. Some vehicles may show about 200 rpm above the target.
• Fluctuating idle—rpm unstable, varying ±100–200 rpm even on a warmed engine. Typical with intake leaks or IAC contamination.
• Engine stalls during braking or stopping—on sudden throttle release or braking, the PCM cannot adjust the mixture in time, causing stalling.
• Harsh automatic transmission shifts—high idle speed creates constant torque, causing abrupt gear changes and accelerated clutch wear.
• The vehicle “pulls” forward at idle—increased braking distance due to the need to counteract engine torque.
• Check Engine light illuminated—constant MIL (Malfunction Indicator Lamp) on.
• Increased fuel consumption—slight rise due to consistently elevated rpm.

How serious is error P0507 and is it safe to drive?

In short: driving cautiously is possible but strongly discouraged. P0507 does not cause immediate catastrophic engine failure but poses several serious risks.

This information is general and does not replace professional consultation.

Risks of continued operation:

• Increased braking distance—the engine continuously produces torque opposing braking, requiring more brake pedal pressure and potentially causing dangerous situations in traffic or at stoplights.
• Risk of unintended acceleration—the vehicle may unexpectedly move forward when releasing the brake, increasing collision risk.
• Harsh automatic transmission shifts and clutch wear—constant high idle rpm stresses the transmission, accelerating internal component wear.
• Accelerated clutch wear—for manual transmissions, aggressive clutch engagement due to high rpm shortens clutch disc life.
• Catalytic converter overheating—if P0507 is accompanied by lean mixture codes (P0171/P0174), the catalytic converter may overheat and sustain damage.
• Increased fuel consumption—constant high rpm raises fuel usage.

When to stop driving immediately:

• Idle speed exceeds 1500–2000 rpm.
• Presence of an unburned fuel smell or engine knocking.
• Vehicle stalls at every stop.
• Idle speed fluctuates by more than 300 rpm.

“High idle speed is not just uncomfortable driving. It signals that the PCM has lost control over airflow. If rpm exceeds 1500 or additional symptoms appear—stop and diagnose. The risk of transmission and catalytic converter damage is real.” – based on certified diagnosticians’ materials (Edmunds, FIXDapp, 2024)

Main causes of error P0507

The primary causes of P0507 range from common (air leaks, throttle contamination) to rare (PCM software faults, engine wear). Understanding this hierarchy helps minimize unnecessary repairs and focus on the most likely sources.

Hierarchy of causes from frequent to rare:

1. Unmetered air intake (vacuum leaks)—the most common cause.
2. Throttle body and IAC valve contamination or malfunction—second most frequent, especially on vehicles with over 100,000 miles (160,000 km).
3. Faulty PCV valve—third cause, causing air leaks through the crankcase ventilation system.
4. EVAP purge valve—fourth cause; a stuck-open valve allows excess air.
5. Electrical problems and sensor faults (TPS, MAF, ECT)—fifth cause.
6. PCM issues and network faults—rare cause.

Airflow path: air filter → MAF (mass air flow sensor) → throttle body → bypass channel with IAC valve → intake manifold → PCV valve (connected to manifold via vacuum hose). Typical leak points: 1) crack in vacuum hose between PCV and manifold; 2) intake manifold gasket leak; 3) IAC-throttle connection; 4) PCV hose at exhaust manifold (for Zetec); 5) EVAP lines to manifold.

Unmetered air intake (vacuum leaks)

Unmetered air intake is air entering the intake system bypassing the MAF sensor. The PCM calculates fuel delivery based on MAF readings, but more air actually enters, leaning the mixture and raising idle speed since the IAC valve cannot compensate.

Typical vacuum leak locations:

• Cracks in vacuum hoses—rubber hoses in PCV, brake booster, EVAP systems crack with age and heat.
• Intake manifold gasket leaks—the gasket between manifold and cylinder head deteriorates over time, causing leaks.
• Damaged hose between throttle and manifold—cracks in corrugated or rubber connections.
• Loose IAC valve or throttle connections—worn sealing rings.

Symptoms of air leaks:

• High idle speed.
• Positive fuel trims (STFT/LTFT)—PCM adds fuel to compensate for a lean mixture.
• Hissing or whistling noises under the hood with the engine running.

Methods to check for air leaks:

1. Smoke machine—introduces smoke at 4.4–7.3 psi (0.3–0.5 bar) pressure into the intake system. Leaks are visually detected by smoke escaping from cracks, hoses, or gaskets.
2. Carburetor cleaner spray—spray around vacuum connections, manifold gaskets, throttle body. If rpm changes or hissing occurs, a leak is found.
3. Soap solution—apply to seams and connections with the engine idling. Bubbles indicate leaks.

Solution: replace damaged hoses, gaskets, sealing rings. Restore airtightness of all intake joints. After repair, check fuel trims with a scanner—they should return to zero or near-zero values.

Idle air control valve malfunction (IAC / ISC)

The idle air control valve (IAC – Idle Air Control, ISC – Idle Speed Control) regulates airflow bypassing the throttle to maintain stable idle speed (usually 700–900 rpm). The PCM adjusts the IAC valve position depending on load (A/C, power steering, electrical loads).

Operating principle:

• The IAC uses a stepper motor to move a plunger or cone in the throttle bypass channel. The PCM calibrates valve position at key-on by sending a series of pulses.
• The ISCV (ISC Valve) has two coils, a permanent magnet on the shaft, and a bimetallic spring. Current through coils T1/T2 rotates the valve element clockwise or counterclockwise at a modulation frequency of 250 Hz.

Common faults:

• Contamination and carbon buildup—carbon deposits, oil film, dirt block plunger or cone movement. The valve sticks open, allowing excess air and raising idle speed.
• Stepper motor sticking—due to corrosion or wear, the motor loses steps, leaving the valve fixed.
• Electrical faults—coil opens or shorts, connector corrosion.

Methods to check IAC:

1. Visual inspection—remove the valve, check for deposits, condition of plunger/cone.
2. Measure coil resistance with a multimeter—normal is typically 40–80 ohms per coil (usually 2–4 coils). Zero or infinite resistance indicates a faulty valve.
3. Active test with scanner—command the PCM to change IAC position and observe rpm. No change indicates sticking or failure.

Cleaning the IAC valve:

1. Remove the valve from the throttle assembly.
2. Spray carburetor cleaner (CR MAX or equivalent) on the plunger, cone, and channel.
3. Wipe with a soft cloth to remove deposits.
4. Air dry the valve (do not use compressed air to avoid coil damage).
5. Reinstall the valve, replace the sealing ring.

Solution: clean if contaminated; replace if electrical fault or mechanical wear. After repair, perform the idle relearn procedure to recalibrate the valve position.

Throttle body contamination or incomplete closure

The throttle body regulates airflow into the engine. Contamination (carbon deposits, oil film from the PCV system) prevents full closure when the accelerator is released, creating an additional air bypass and raising idle speed.

Causes of contamination:

• Oil vapors from the PCV system.
• Carbon deposits from fuel and EGR.
• Dirt entering through the air filter.

Consequences:

• Throttle does not fully close, allowing excess air.
• Throttle shaft sticking.
• Incorrect throttle position stored in PCM memory after prolonged contamination.

Diagnosis:

1. Visual inspection—remove the air duct and inspect the throttle edge. Black deposits or oily film indicate contamination.
2. Throttle angle check with scanner—compare actual throttle closing angle with target (typically 0–2° with pedal released). Angle >5° may indicate incomplete closure.

Throttle cleaning:

1. Remove the throttle assembly (for mechanical systems) or leave it in place (for electronic throttle control, ETC).
2. Spray throttle body cleaner.
3. Wipe the throttle plate and channel with a soft cloth.
4. For ETC, avoid forcing the actuator—clean only the plate and idle air channel (IAC).
5. Dry the assembly and reinstall.

Throttle adaptation (idle relearn):

After cleaning ETC systems, adaptation is often required to recalibrate the throttle base position. Procedure varies by manufacturer:

• General procedure:

1. Warm the engine to operating temperature (176–203°F / 80–95°C).
2. Turn off ignition for 10 seconds.
3. Turn ignition on (engine off), hold accelerator fully pressed for 5 seconds.
4. Release pedal, turn off ignition for 10 seconds.
5. Start engine, let idle stabilize for 20 seconds (target 700±50 rpm).

• For Nissan HR16DE: disconnect battery terminal for 15 minutes, then warm engine for 10 minutes to reset deep PCM trims.

Solution: throttle cleaning plus adaptation. Replace the throttle assembly if actuator or shaft is worn.

Crankcase ventilation system faults (PCV)

The positive crankcase ventilation (PCV) system vents crankcase gases back into the intake manifold. The PCV valve regulates gas flow using intake vacuum.

How PCV faults cause P0507:

• A stuck-open or damaged PCV valve allows excess air from the crankcase into the intake, creating a vacuum leak.
• A torn PCV diaphragm increases leakage, adding unmetered air.
• The PCM detects this as an air leak, raising idle speed above target by about 100 rpm or more.

Symptoms of faulty PCV:

• High idle speed.
• Hissing or whistling noises under the hood.
• Oil deposits in crankcase ventilation hoses.
• Positive fuel trims (STFT/LTFT).

PCV check:

1. Pinch crankcase ventilation hose—while idling, pinch the hose between PCV valve and intake manifold. If rpm drops by 50–100 rpm, the valve leaks air.
2. Inspect PCV diaphragm—remove valve and check for cracks or tears.
3. Check one-way valve—shake PCV valve; a functional valve produces a characteristic clicking sound.

Solution: replace PCV valve and/or diaphragm, clean ventilation hoses. After replacement, verify fuel trims return to zero.

Evaporative purge valve (EVAP purge valve): diagnosis

The EVAP purge valve controls fuel vapor flow from the charcoal canister into the intake manifold. If stuck open or EVAP lines are damaged, excess air bypasses the MAF sensor, causing the PCM to detect an air leak and raise idle speed.

Quick tests:

1. Pinch EVAP hose at idle—pinch the hose between canister and intake manifold. A 50–100 rpm drop indicates a leak via EVAP line or purge valve.
2. Active test with scanner—command “close purge.” Normal response is that rpm and positive fuel trims decrease. No response indicates valve sticking or line leak.
3. Visual inspection and fuel smell—check canister and lines for cracks, listen for hissing. Fuel odor near canister indicates leaks.

Solution: replace purge valve or damaged EVAP lines. Verify fuel trims after repair.

Sensor and wiring issues affecting idle speed

MAF (mass air flow), TPS (throttle position sensor), and ECT (engine coolant temperature) sensors and their wiring can cause incorrect signals due to faults or connector corrosion. The PCM may miscalculate target idle speed or fuel delivery, leading to elevated rpm.

Typical problems:

• Connector corrosion and wiring breaks—contact corrosion, harness fractures, poor grounds.
• Sensor readings out of range—for example, a MAF reporting excessive airflow causes the PCM to add fuel and air, raising rpm.
• TPS faults—incorrect throttle angle signals make the PCM think the throttle is partially open.

Check methods:

1. Read live data with scanner—compare sensor readings to reference values (see table below).
2. Wiggle test—move wiring harnesses with engine running and observe scanner data. Fluctuations indicate breaks or poor contacts.
3. Multimeter check—measure sensor resistance, supply voltage, and signal output.

Solution: clean corrosion from connectors, restore good grounds, replace sensors out of specification.

Note: MAF and TPS values depend on engine size and manufacturer scale. Always consult the manufacturer’s manual or specifications for the specific model. The ranges given are approximate.

Step-by-step diagnosis and fixing of P0507 DIY

Procedure follows a “from simple to complex” principle—how to fix and clear P0507 in a garage setting:

This information is general and does not replace professional consultation.

Quick tests (low-effort)

Before deep diagnostics, perform 5 quick checks:

1. Wiggle test harnesses—move TPS/MAF/IAC wiring at idle and watch live data. Fluctuations indicate contact or wiring issues.
2. PCV valve—pinch PCV hose at idle; rpm drop indicates air passing through PCV.
3. EVAP line—pinch EVAP hose to manifold; observe rpm and fuel trims.
4. Spray test—carefully spray cleaner around joints/gaskets; temporary idle change indicates leak.
5. IAC/ETC active test—command idle changes via scanner; no response indicates sticking or failure.

Step 1. Scanner diagnosis

Read fault codes and freeze-frame data (snapshot at code setting). Check live data: idle rpm, fuel trims (STFT/LTFT), MAF, TPS, ECT readings.

• Reference: idle rpm 600–900, STFT/LTFT ±5–10%. MAF and TPS depend on engine size and model—consult manufacturer manual.
• Deviation: rpm >1000, positive trims >15% indicate an air leak; TPS >20% (or throttle angle >5°) may indicate incomplete throttle closure.

Do not clear the code yet—freeze-frame helps understand conditions when the PCM set P0507.

Step 2. Check for air leaks and EVAP valve

Inspect intake tract with a smoke machine or spray carburetor cleaner around:

• vacuum hoses (PCV, brake booster, EVAP);
• intake manifold gasket;
• throttle and IAC connections.

If rpm changes or hissing occurs, a leak is found.

EVAP check:

• Pinch EVAP hose to manifold at idle; an rpm drop of 50–100 indicates a leak via the EVAP line or purge valve.
• Active scanner test: command “close purge”; normal response is that rpm and fuel trims decrease.

Fix leaks by replacing damaged hoses, gaskets, seals; tighten clamps. Replace EVAP purge valve if needed.

Step 3. Throttle cleaning

Remove throttle assembly (mechanical systems) or leave it in place (ETC). Spray throttle body cleaner on plate and bypass channel. Wipe with a soft cloth, dry, reinstall.

After assembly, ETC systems may require throttle adaptation (idle relearn):

1. Warm engine to 176–203°F (80–95°C).
2. Turn off ignition for 10 seconds.
3. Turn ignition on, hold accelerator 5 seconds, release, turn off ignition for 10 seconds.
4. Start engine, let idle stabilize for 20 seconds.

Note: ETC vehicles do not use a separate IAC valve—the bypass is controlled by the throttle plate. For mechanical throttles, clean IAC separately (see Step 4).

Step 4. IAC valve (for mechanical throttle)

Note: ETC vehicles do not have an IAC valve. Proceed to Step 5.

Remove valve, clean with carburetor cleaner, wipe plunger/cone and channel. Measure coil resistance with a multimeter (typically 40–80 ohms per coil). Replace valve if resistance is zero or infinite.

Perform active scanner test: command the PCM to move IAC and observe rpm. No change indicates a sticking valve.

Step 5. Sensors and wiring

Evaluate MAF, TPS, ECT readings with scanner. Compare to reference values (see table above). Check sensor power and ground with multimeter. Perform wiggle test on harnesses.

Fix wiring breaks and corrosion; replace sensors out of tolerance.

Step 6. Clear code and test drive

Clear code with scanner (battery disconnect not recommended as it erases long-term adaptations). Then:

• Warm engine at idle for 2–3 minutes.
• Test drive for 10–15 minutes with varied conditions (acceleration, braking, idling at stoplights).

Check if code returns. If P0507 does not reappear, the issue is resolved.

Step 7. Monitoring and advanced diagnostics

If code returns after steps 1–6:

• Measure cylinder compression (specification depends on engine model).
• Check timing phases (possible VVT system fault).
• Check PCM software version—updates or Technical Service Bulletins may be available.
• Consult a professional diagnostician for in-depth analysis.

Safety precautions

Precautions during diagnosis and repair:

• Work on a cold engine when spraying cleaners—hot surfaces can ignite aerosols.
• Ensure good ventilation—cleaner vapors are toxic.
• Do not force the electronic throttle manually—it may damage the ETC actuator.
• Wear eye and skin protection—use goggles and gloves when handling cleaners.
• Avoid sparks and open flames—sprays are flammable.
• Secure the vehicle during high idle—use the parking brake and wheel chocks.

Related codes and differential diagnosis

Related fault codes and cross-diagnosis

P0507 often appears with other codes. Code combinations indicate likely root causes:

Diagnostic logic:

• If P0507 + P0171/P0174—prioritize air leak search (vacuum hoses, gaskets, EVAP, PCV). Positive fuel trims (LTFT >+15%) support a lean condition.
• If P0507 without lean codes but high TPS% at idle—problem with throttle or adaptation. Check throttle angle with scanner; perform cleaning and adaptation.
• If P0507 + P0505—general idle system check: leaks, throttle, IAC (mechanical throttle) or ETC (electronic throttle).
• If P0506 (low idle) alternates with P0507—possible PCM/adaptation fault or unstable IAC/ETC operation.

Common mistakes to avoid when fixing P0507

• Replacing parts “at random”—changing IAC valve or sensors without checking for air leaks and reading live data leads to unnecessary costs and does not fix the root cause.
• Cleaning throttle without adaptation—after ETC throttle cleaning, rpm may rise to 2100–2500 if adaptation is not performed. The PCM accumulates contamination trims, which become invalid after cleaning.
• Ignoring PCV, EVAP, and small hose cracks—many focus only on throttle and IAC, missing vacuum leaks via PCV or EVAP systems and minor hose cracks.
• Disconnecting battery instead of finding the source—battery removal may temporarily stabilize rpm but does not fix the cause. Proper approach is to locate and fix the problem, then clear the code with a scanner.
• Skipping ground and connector checks—poor ground or corroded connectors cause intermittent symptoms. Wiggle test and multimeter checks are mandatory.
• Skipping EVAP check—the EVAP purge valve is a common cause of P0507 but often overlooked during diagnosis.

P0507 specifics on different vehicles

Ford: features, causes, and adaptations

Typical cause: throttle and PCV contamination. Frequent cases of IAC valve sticking.

Adaptation: after throttle cleaning, Idle Learn procedure is mandatory:

1. Warm engine to operating temperature.
2. Idle for 2–3 minutes with loads on (lights, A/C, rear defroster).
3. Turn off all loads, idle for another 1–2 minutes.

Technical Service Bulletins (TSB): monitor PCM calibration updates on Ford’s official site or through a dealer. Some models (especially EcoBoost) have TSBs for throttle operation correction.

Nissan/Infiniti: electronic throttle and idle learning

Typical cause: electronic throttle contamination. Minor vacuum leaks cause significant idle speed increase.

Adaptation: critical procedures are Throttle Valve Closed Position Learn and Idle Air Volume Learn:

1. Warm engine to 176–203°F (80–95°C).
2. Turn off ignition for 10 seconds.
3. Turn ignition on (engine off), hold accelerator fully pressed for 5 seconds.
4. Release pedal, turn off ignition for 10 seconds.
5. Start engine, idle for 20 seconds.

Note: Nissan HR16DE may show idle up to 2100–2500 rpm after throttle cleaning before adaptation.

Hyundai/Kia: throttle and PCV

Typical cause: throttle carbon buildup and PCV diaphragm damage.

Adaptation: short idle learning after throttle cleaning:

1. Warm engine.
2. Turn off ignition for 10 seconds.
3. Start engine, idle 2–3 minutes.

Fuel trims check: after cleaning, verify STFT/LTFT with scanner—they should return to about ±5%.

GM (Chevrolet, Buick, Cadillac, etc.)

Typical cause: vacuum leaks and throttle contamination. GM systems may set P0507 when idle speed exceeds target by about 200 rpm or more.

Adaptation: vehicles with electronic throttle (TAC) may require Throttle Learn after cleaning:

1. Warm engine to operating temperature.
2. Turn off ignition for 10 seconds.
3. Turn ignition on (engine off) for 30 seconds (PCM calibrates throttle base position).
4. Start engine, idle 2–3 minutes.

Check: ensure throttle angle at idle is typically 0–2°.

Toyota/Lexus: ETCS-i (Electronic Throttle Control System)

Typical cause: throttle and IAC valve contamination (for older mechanical throttle models). For ETCS-i, carbon deposits on the throttle plate.

Adaptation: for ETCS-i systems after cleaning:

1. Warm engine to operating temperature.
2. Turn off ignition for 10 seconds.
3. Turn ignition on (engine off), hold accelerator fully pressed for 15 seconds.
4. Release pedal, turn off ignition for 10 seconds.
5. Start engine, idle 20 seconds.

Note: some Toyota models require a scanner for forced adaptation via “Utility” or “Relearn” menu.

VW/Audi: ETS (Electronic Throttle System)

Typical cause: throttle contamination and vacuum leaks (especially via EVAP and PCV).

Adaptation: ETS requires a scanner with Basic Settings function (throttle adaptation):

1. Warm engine to operating temperature.
2. Connect scanner, select “Engine” → “Basic Settings” → “Channel 060” (Throttle adaptation).
3. Follow scanner instructions (do not touch accelerator).
4. After adaptation, idle for 2–3 minutes.

Check: throttle angle at idle should typically be 0–3°.

VAZ/GAZ: IAC and hoses

Typical cause: air leaks after maintenance (gasket, hose replacement) and IAC wear.

Check: pay attention to brake booster vacuum adapter, intake manifold gasket, PCV hoses.

Adaptation: most VAZ/GAZ models with mechanical throttle do not require adaptation after cleaning. Cleaning IAC and restoring intake airtightness is sufficient.

Required tools and software for diagnostics

• OBD-II scanner with live data and active tests—for reading codes, freeze-frame, real-time monitoring (rpm, MAF, TPS, fuel trims), and performing active IAC/ETC tests.
• Smoke machine or carburetor cleaner—for detecting vacuum leaks. Smoke machine supplies smoke at 4.4–7.3 psi (0.3–0.5 bar); carb cleaner sprayed on joints detects rpm changes.
• Multimeter—for checking IAC coil resistance, sensor power and signal (MAF, TPS, ECT).
• Tool kit: clamps, vacuum hoses (for replacement), throttle body cleaners (throttle body cleaner, CR MAX).
• Service software/app for adaptations—to perform Idle Learn, Throttle Valve Closed Position Learn, Basic Settings. Examples: manufacturer apps (Nissan DataScan, FORScan for Ford, VCDS/ODIS for VW/Audi), universal scanners with adaptation functions (Autel MaxiSys, Launch X431).

Recommended scanners:

• For basic diagnostics and DIY—ELM327 + Torque or BlueDriver.
• For professional diagnostics with adaptations—Autel MaxiSys or Launch X431.
• For brand-specific needs—FORScan (Ford), VCDS/ODIS (VW/Audi), Nissan DataScan (Nissan).

Prevention and scheduled idle maintenance

Prevention: how to avoid P0507 recurrence

Preventive measures to avoid P0507:

• Regular intake maintenance: clean throttle body and idle air channel every 12,000–18,000 miles (20,000–30,000 km) under intensive use (city driving, short trips) or every 62,000 miles (100,000 km) under mild use.
• Inspect and replace vacuum hoses, gaskets, clamps: check for cracks and leaks every 25,000–31,000 miles (40,000–50,000 km).
• Use quality fuel: avoid fuel with high sulfur content or additives that increase deposits.
• Timely oil and filter changes: clean engine oil reduces oil vapor formation in the PCV system.
• Regular PCV maintenance: check PCV valve, diaphragm, hoses every 25,000–31,000 miles (40,000–50,000 km).
• Check EVAP purge valve and lines for leaks every 25,000–31,000 miles (40,000–50,000 km).
• Update PCM software: monitor Technical Service Bulletins (TSBs) and calibration updates at authorized dealers.

Usage conditions specifics:

• City vs highway: throttle cleaning is more frequent in city/short-trip use (every 12,000–18,000 miles / 20,000–30,000 km); less frequent on the highway (every 62,000 miles / 100,000 km).
• Turbocharged vs naturally aspirated: turbo engines require more frequent PCV and vacuum line checks (every 18,000 miles / 30,000 km) due to higher crankcase gas pressure.

Post-maintenance check:

• After gasket, hose, or throttle replacement, verify all connections are secure and airtight.
• Ensure all sensor connectors are plugged in and secured.