- P0507 signals higher-than-normal idle RPM detected by the PCM
- Normal idle is 650–850 RPM; sustained higher idle triggers the code
- Common causes: throttle carbon buildup, IAC issues, vacuum leaks, electrical faults
- Diagnosis should begin with throttle body cleaning before replacing parts
P0507 is one of the most common OBD2 codes related to idle issues. It triggers when the PCM (Powertrain Control Module) detects that the engine is running at an idle RPM higher than programmed.
When the engine runs in idle vacuum, it should maintain a stable and constant idle speed, typically between 650–850 RPM. If this value is consistently exceeded, the engine management system will log the P0507 code and illuminate the service light.
What the P0507 error code means
The PCM continuously monitors engine performance and expects the engine to idle at a specific RPM. This value is programmed in the ECU software and varies with engine temperature, electrical load, and other factors.
When the RPM does not fall within normal parameters and remains persistently high at idle, the PCM will initially try to correct this by adjusting the air intake control system. If it cannot keep the RPM within acceptable limits, it will store the P0507 code and illuminate the service light on the dashboard.
Symptoms of the P0507 error code
The main signs indicating the presence of this code include:
- High and unstable idle - the engine runs at higher RPM than normal when the vehicle is stationary
- Idle does not drop when the accelerator pedal is released
- The engine does not shut off immediately after key off (diesel run-on)
- High fuel consumption due to increased RPM
- Check engine light on on the dashboard
- Abnormal engine vibrations at idle
- Cold start difficulties in some cases
Common causes of the P0507 code
Carbon buildup on the throttle body
This is by far the most frequent cause of P0507. Carbon deposits and grime around the throttle plate prevent it from fully sealing, allowing excessive air into the engine.
Idle Air Control IAC valve problems
The idle air control valve can be:
- Stuck in an open position due to deposits
- Electrically faulty
- Mechanically worn after many kilometers of operation
Vacuum leaks in the intake system
Any vacuum leak lets uncontrolled air into the engine:
- Cracked or disconnected vacuum hoses
- Deteriorated intake manifold gaskets
- Defective PCV valve
- Damaged air intake hoses
Electrical issues
- Broken or shorted circuits in IAC wiring
- Corroded or disconnected connectors
- Issues with the throttle position sensor
Less common causes
- Defective PCM (very rare)
- Faulty air temperature sensor
- EGR system problems
Common incorrect diagnosis
Many technicians make the mistake of replacing the IAC valve or other components without first checking the throttle body. This approach can lead to misdiagnosis and unnecessary repair costs.
Recommendation: Always start diagnosis with cleaning the throttle body before replacing any component.
Step-by-step diagnostic process
Equipment needed
- OBD2 scanner or code reader
- Digital multimeter
- Throttle body cleaner spray
- Basic hand tools for removal
Diagnostic steps
1. Initial visual inspection
Begin with a thorough visual check of:
- All wiring and connectors in the engine area
- Vacuum hoses for cracks or disconnections
- The throttle body for visible deposits
Repair any obvious damage before continuing.
2. Read and clear codes
Connect the OBD2 scanner and:
- Record all stored codes (including pending)
- Note freeze frame data for context
- Clear codes from memory
- Start the engine and check if the code reappears immediately
3. Test with the IAC connector disconnected
- Turn off the engine and disconnect the electrical connector from the IAC valve
- Start the engine and check if the P0507 reappears
- If the code does not reappear, the IAC valve likely has an internal short and must be replaced
4. Check electrical signals
If the code persists with the IAC disconnected:
- Use the scanner to command the IAC open/close
- Measure voltage and ground at the IAC motor connector with a multimeter
- Values should be within the manufacturer specifications (usually around 12 V)
5. Test circuit resistance
If there is no voltage at the IAC connector:
- Turn off the engine and disconnect the PCM connector
- Measure the circuit resistance with a multimeter
- Abnormal values indicate wiring problems requiring repair
Solutions and repairs
Cleaning the throttle body
This is the first and most important repair to try:
- Remove the air filter housing
- Locate the throttle body
- Use a special throttle body cleaner spray
- Carefully wipe away carbon deposits with a clean rag
- Allow to dry completely before reassembly
Replacing the IAC valve
If cleaning does not solve the problem:
- Locate the IAC valve (usually near the throttle body)
- Disconnect the electrical connector and vacuum hoses
- Replace with an original part or a quality equivalent
- Recalibrate the system per the manufacturer procedure
Repairing vacuum leaks
- Replace all damaged vacuum hoses
- Inspect and replace intake manifold gaskets if needed
- Test the system with a vacuum leak detector
Preventing future issues
To avoid a recurrence of P0507:
- Regularly maintain the air filter as a clogged filter makes the engine work harder
- Use quality fuel and fuel system cleaners
- Perform periodic service according to the manufacturer schedule
- Clean the throttle body periodically (every 30,000–50,000 km)
- Check vacuum hoses at every service
Estimated repair costs
- Throttle body cleaning: 150–300 RON (service)
- IAC valve replacement: 300–800 RON (parts + labor)
- Wiring repairs: 200–500 RON depending on complexity
- Professional diagnostic: 100–250 RON
The P0507 error code is generally easy to resolve if you follow a systematic diagnostic approach. Most cases are resolved by simply cleaning the throttle body, making this the first solution to try before investing in replacement parts.
