What this code means
This code means the PCM may be seeing the engine idle higher than the idle speed it is trying to control.
What the vehicle may do
- The MIL may be illuminated.
- The engine may idle higher than expected.
- Stop/start may be disabled when the code is active on equipped vehicles.
Possible fault areas
- Possible PCV system leaks or other unmetered air leaks.
- Possible throttle body control, restriction, or connector issues.
- Possible ABS communication or vehicle-speed data issues that can affect idle-speed logic.
- Possible PCM-related concern after the rest of the diagnostic path checks clean.
Diagnostic path
Code logic and symptom context
For this Ram 1500 with the 5.7 gas engine, P0507 means the PCM is seeing idle speed higher than expected. In plain terms, the PCM is trying to control idle, but actual engine speed can stay above the target. The customer may notice a high idle, the MIL may be on, and if the truck has stop/start, that system is disabled while this code is active. Broadly, this can involve unmetered air through the PCV system or another vacuum leak, throttle body control or connector issues, ABS communication or data that affects the PCM’s vehicle-speed logic, or finally a PCM concern after the rest of the path checks clean. The monitor runs with the engine idling, no throttle input requested, vehicle speed equal to zero, and engine run time of more than 30.0 seconds. The code sets when engine speed is more than 200 rpm above idle speed for 30.0 seconds.
Start with basic checks and confirm the fault
Start with the basic system checks before getting into the fault tree. Then use the scan tool to read DTCs in all ECUs, record what is present, and save the scan data you may need later. Erase the codes, turn the ignition off for a minimum of 10.0 seconds, then turn it back on. Using the captured operating conditions and the monitor conditions for this code, operate the vehicle in the conditions that set the fault, then read the codes again. If P0507 comes back, continue the diagnosis. If it does not come back, treat it as an intermittent condition and do not guess at a hard failure.
Check for faults that can mislead this diagnosis
Next, look back at the recorded codes. If active or pending throttle body faults are present, handle those first. Also check for ABS module faults that affect communication or vehicle-speed information. A loss of communication with the ABS module can make the PCM default vehicle speed to zero while driving, and that can falsely fail the idle-speed rationality check. If those faults are present, correct them before continuing with the P0507 path. If they are not present, move on to the air and throttle checks.
Inspect the PCV system
Turn the ignition off and inspect the PCV system. Look for leaks, cracked or damaged hoses and tubes, poor hose or tube connections, and a PCV valve stuck open. If you find a PCV system problem, repair it as needed, then verify the repair and confirm the code stays gone. If the PCV system checks clean, continue to the vacuum leak inspection.
Check for vacuum leaks
Now start the engine and check for vacuum leaks. While the engine is running, stay out of the direct line of the fan, keep your hands away from pulleys, belts, and the fan, and do not wear loose clothing. Inspect for internal leaks and for external components that can create a vacuum leak, including vacuum supply lines, the brake booster, the purge solenoid, and engine seals. If you find a vacuum leak, repair it as needed, then verify the repair and confirm the code stays gone. If no vacuum leak is found, continue to the throttle body check.
Check throttle body operation
Next, inspect the throttle body for carbon buildup, other restrictions, and a bent throttle plate. Use a straight edge when checking the plate. If the throttle plate does not close entirely, it may be bent. With the vehicle running, wiggle-test the ETC motor wiring and connections, and listen for the idle to raise or fluctuate. If you find a throttle body problem, or the idle changes during the wiggle test, verify good pin-to-terminal contact at the throttle body and PCM connectors. If the connectors check out and no connector problem is found, the path calls for replacing the throttle body assembly. Disconnect the battery when replacing the throttle body assembly. After installation, use the scan tool and run Throttle Body Self Learn, then verify the repair and confirm the code stays gone. If no problem is found and the idle does not fluctuate during the wiggle test, continue to the PCM and harness connection checks.
Check PCM and related connections
At this point, take care of any applicable bulletins, then inspect the related PCM and component connections. Disconnect the PCM harness connectors, any related in-line connectors if equipped, and the related component connectors. Check the connectors and terminals for proper seating and installation, damaged locks, corrosion or water intrusion, seal damage, bent terminals, heat damage from a poor connection, pushed-back terminals, spread terminals, and proper terminal tension. Repair any conditions you find. Then reconnect the PCM connectors, any in-line connectors, and the related component connectors, making sure everything is fully seated and the locks are fully engaged. Erase the codes, test drive or operate the vehicle under the monitored and fault-setting conditions, and read the codes again.
Final decision and verification
If P0507 returns after the connector inspection, repairs, reconnection, code erase, and repeat operation under the correct conditions, the path calls for replacing and programming the PCM, then verifying the repair. If the code does not return, the wiring or poor connection problem has been corrected. Keep verification separate from the testing: after the repair, confirm normal operation and make sure P0507 stays gone. Takeaway: this code is a commanded-versus-actual idle-speed problem, so prove the fault first, rule out related throttle and ABS faults, then work through unmetered air, throttle body operation, connections, and only then the PCM. For more diagnostic training, visit stepdiagnostics.com.
Final check
P0507 is often approached by confirming the fault, checking related faults first, then working through air leaks, throttle body operation, connections, and final control-module decisions only after.K
For more guided automotive diagnostics, visit STEP Diagnostics.
