P0507 Idle Air Control System RPM Higher Than Expected

• P0507 Technical Definition: Idle Air Control System RPM Higher Than Expected
• P0507 Meaning: Idle Air Control cannot adjust idle speed properly
• Most common cause: Failed or Dirty Idle Air Control/Electronic Throttle Body
• Risks for the engine/driver: Low. Get it checked out as soon as you can
• Emissions severity: HIGH. The car won’t pass emissions testing
• Estimated repair time: 1 days
• Estimated repair cost: $100+

The engine code P0507 is stored in memory when the Electronic Control Unit (ECU) senses an idle speed much higher than its normal value.

The Idle Air Control System adjusts the engine idle speed by means of a motorized by-pass valve known as the Idle Air Control (IAC) or by means of an Electronic Throttle Body (ETB). Some vehicles even use both the IAC and the ETB.

The ECU uses the Idle Air Control System to keep the actual idle speed as close as possible to its expected value. It’s not uncommon for the IAC and/or ETB to becoming dirty with carbon and oil deposits thus decreasing its response time. This dirt, and other problems like air/vacuum leaks can increase the idle speed beyond what the ECU can control.

The P0507 code is set when the ECU detects a significative variation on the expected idle speed after trying to adjust it.

The most common symptoms of data trouble code P0507 are:

1. Check Engine Light (CEL).
2. Idle speed higher than normal.
3. Difficulty during engine start, in some cases even a no start condition.
4. Poor fuel economy.
5. Rough idle.
6. Gas smell from the exhaust pipe.
7. Possible engine misfire (if an air leak is present).

The most common causes of data trouble code P0507 are:

• IAC wiring (open, shorted, burnt) 
• IAC connector (loosely, corroded, disconnected or bent pins)
• ETB wiring (open, shorted, burnt) 
• ETB connector (loosely, corroded, disconnected or bent pins)
• Dirty, stuck or clogged IAC (oil, carbon deposits)
• Dirty, stuck or clogged ETB (oil, carbon deposits)
• A vacuum leak after the ETB/MAF
• A vacuum leak in the EGR valve
• Bad IAC 
• Bad ETB 
• Bad EVAP 
• Bad PCV valve
• Bad or deficient power steering pressure switch
• Bad or deficient Engine Coolant Temperature sensor (ECT) 
• Deficient charging system (alternator)

For the purpose of this article, it’s assumed that you have a basic knowledge of safety precautions while working on your vehicle.

Always refer to the appropriate OEM literature when possible. Original manufacturer diagnostic procedures should always have precedence over a generic workflow.

That said, let’s start the diagnostic process!

1. Preliminary steps

To discard a possible intermittent DTC condition, you’ll need to clear the ECU memory and complete a driving cycle.

• Read data trouble codes and take note of them.
• Clear data trouble codes memory.
• Perform a driving cycle (at least 5-10 minutes).

If the Check Engine Light stays off then you may have an intermittent problem. If the light comes on during your driving cycle then continue with the diagnostic process.

2. Visual Inspection

> IAC condition: to inspect the IAC condition you will need to remove it from the vehicle. Usually, the Idle Air Control is located on the throttle body. Look for oil, dirt and/or carbon deposits on its tip. Clean the IAC with extreme care and re-install it on the vehicle. Repeat step 1 to check if the problem is solved.

> IAC wiring and connector: perform a meticulous visual inspection of the Idle Air Control wiring and connectors. Look for burnt, damaged, corroded or deteriorated wires, also unplug the actuator and look for bent terminal pins, loosely connections, corrosion or any other possible indication of a bad connection.

> ETB condition: to inspect the ETB condition you will need to remove the intake air hose connected to the throttle body. Look for oil, dirt and/or carbon deposits. Clean the ETB with extreme care, only use safe decarbonizing products. Repeat step 1 to check if the problem is solved.

> ETB wiring and connector: perform a meticulous visual inspection of the Electronic Throttle Body wiring and connectors. Look for burnt, damaged, corroded or deteriorated wires, also unplug the actuator and look for bent terminal pins, loosely connections, corrosion or any other possible indication of a bad connection.

> Vacuum hoses: perform a meticulous visual inspection of all vacuum lines, including MAP sensor, PCV, brakes vacuum booster, fuel pressure regulator, etc. Also, check the air intake hose looking for any sign of deterioration or leak.

> Exhaust Gas Recirculation valve inspection: perform a thorough inspection of the EGR valve exterior, tubing, and connections. Look for possible exhaust leaks in the EGR gasket and connections. Replace the gasket and/or EGR valve if necessary.

> PCV valve inspection: remove the PCV valve from the vehicle and check its condition. Replace as necessary.

Fix any wiring problem before continuing.

3. Electrical Tests

> IAC electrical tests: using the appropriate OEM literature, check the ground, and supply voltage for IAC stepper motors. Most IAC consists of two internal coils, one controlling each direction, resulting in a four-cable design.

> ETB electrical tests: using the appropriate OEM literature, check the ground, supply voltage, reference voltage, and throttle actuator control lines. Most ETB includes the Throttle Position Sensor (TPS) wiring, so you will need to check it too.

> Power Steering Pressure Switch electrical tests: using the appropriate OEM literature, check the PSP line(s). This sensor usually has one or two cables.

> ECT electrical tests: using the appropriate OEM literature, check the Engine Coolant Temperature wiring. Please refer to our ECT article for more details.

> Charging System electrical tests: using the appropriate OEM literature, check the alternator wiring. Please refer to our Charging System article for more details.

4. Scan Tool Tests

> Idle Air Control functional test: depending on your vehicle and automotive scanner, you should be able to perform an IAC “functional test”. Once you are ready, start the engine to enter KOER mode. Select the IAC test and then manipulate the engine RPM. Try to set an idle speed close to the factory preset. If you notice a lag on the IAC response or a failure to control the idle speed then re-check its condition. Replace as necessary.

> Electronic Throttle Body functional test: depending on your vehicle and automotive scanner, you could be able to perform an ETB “functional test”. Once you are ready, start the engine to enter KOER mode. Select the ETB test and then manipulate the engine RPM. Try to set an idle speed close the factory preset. In case you notice a lag on the ETB response or a failure to control the idle speed then re-check its condition. Replace as necessary.

Depending on the diagnostics results you may need to do the following:

• Repair the IAC (Idle Air Control) wiring and/or connectors.
• Cleaning the IAC 
• Repair the ETB (Electronic Throttle Body) wiring and/or connectors.
• Cleaning the ETB 
• Repair an intake manifold leak
• Repair an EGR leak
• Replace the IAC 
• Replace the ETB 
• Replace the PCV
• Replace the PSP
• Replace the ECT
• Repair/Replace the alternator