P0507: P0507 Diagnostic Guide

What this code means

P0507 may mean the engine is idling higher than the control module wants during idle control.

What the vehicle may do

The vehicle may idle too high.
The idle may hang after deceleration.
The driver may notice a raised or unstable idle.

Possible fault areas

Possible unmetered air or vacuum leak areas.
Possible throttle valve closing issue.
Possible crankcase ventilation routing or vacuum leak issue.
Possible intermittent vehicle speed signal concern.

Diagnostic path

Opening context

On this 2014 to 2018 GMC Sierra 1500 with the 5.3 gas engine, P0507 is a high idle concern. In plain terms, the engine control side may be seeing actual idle speed higher than the idle speed it wants. The truck may idle too high, hang on decel, or feel like the idle is being held up. Broadly, this can involve unmetered air, a throttle valve that is not closing the way it should, crankcase ventilation issues, or sometimes an intermittent vehicle speed signal. The key is to prove commanded idle versus actual idle before chasing parts.

Start with the basic checks

Start with the basic system checks, then follow a structured diagnostic approach so you are not diagnosing this code in isolation. Turn the ignition ON and look for any other codes. If other codes are present, check what they mean first. If no other codes are set, continue with the P0507 path. Treat the running conditions as monitor gates, not as the repair. The engine is operating for 60 s or greater, the engine is idling for greater than 5 s, the barometric pressure is greater than 70 kPa (11 psi), the engine coolant temperature is warmer than 60°C (140°F), the intake air temperature is warmer than −20°C (−4°F), the vehicle speed is less than 1.6 km/h (1 mph), the commanded engine speed is steady within 25 RPM, the manual transmission clutch pedal position is less than 25 percent or greater than 88 percent if equipped, and system voltage is between 11–32 V. Once the conditions are met for greater than 10 s, this monitor runs continuously. P0507 sets when actual idle speed is approximately 188 RPM greater than desired idle speed.

Check idle airflow compensation

With no other codes leading you elsewhere, check the scan tool Throttle Body Idle Airflow Compensation parameter. It should be less than 90 %. If it is 90 % or greater, the next path is throttle body cleaning. If it is less than 90 %, bring the engine to idle at normal operating temperature and continue the idle comparison.

Compare actual idle to desired idle

Before comparing actual and desired engine speed, let the engine run for greater than 60 s, then let it idle at a steady state for an additional 10 s. First, verify actual Engine Speed is not 100 RPM less than Desired Idle Speed. That low-side check is part of the shared idle-speed path. For this high-idle code, if actual Engine Speed is 100 RPM greater than Desired Idle Speed, continue into the high-side decision. Actual Engine Speed must not be 200 RPM greater than Desired Idle Speed. If actual speed is 200 RPM or greater above desired, move into the circuit and system checks. If actual speed is within 200 RPM of desired, reproduce the operating conditions, or the captured conditions from when the fault happened, and verify the code does not reset. If a code does reset, pause and diagnose what is setting instead of guessing.

System checks

The shared idle-speed testing path also gives useful contrast. On the low-idle side, the checks are for a restricted exhaust, mechanical conditions that limit engine speed, or a parasitic load on the engine such as a transmission condition or a belt driven accessory condition. For P0507, stay focused on the high-idle causes: verify that the high idle is not being caused by a vacuum leak, and verify that the throttle valve closes correctly. Then check the crankcase ventilation system operation. Look for improper PCV routing and vacuum leaks in the PCV system. If one of these conditions is found, repair that condition as needed. Also keep in mind that an intermittent vehicle speed sensor signal can cause P0507 to set, so do not ignore that possibility if the idle-air checks are not explaining the code.

Verify the repair

Keep verification separate from testing. After the repair is complete, verify the repair and confirm the code stays gone under the proper operating conditions. The takeaway is simple: for P0507, prove the idle command versus actual speed, check the airflow compensation decision point, then look for extra air through vacuum leaks, throttle closure, or the PCV system before calling it fixed. For more diagnostic training, visit stepdiagnostics.com.