Severity and Symptoms
The TPS plays an important role in engine operation, therefore, a stored P2124 code should be treated with a certain degree of urgency.
Symptoms of a P2124 code may include:
- Hesitation during acceleration
- Black smoke from engine exhaust (especially at startup)
- Delayed engine starting (particularly during cold starts)
- Reduced fuel efficiency
- Stored emission-related codes may accompany a P2124
Possible causes of this engine code include:
- Faulty or improperly adjusted TPS
- Open or shorted TPS “D” wires or connectors
- Binding or damaged throttle plate
- Incorrect PCM or PCM programming error
Diagnostic and Repair Procedures
A good starting point is always to check the Technical Service Bulletins (TSBs) for your specific vehicle. Your issue may be a known problem with a known fix published by the manufacturer and can save you time and money during diagnosis.
I typically use a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable vehicle information source (ALL DATA DIY) to diagnose a P2124 code.
Successful diagnosis usually begins with a visual inspection of all cables and connectors related to the system. I also like to test the throttle plate for signs of coking or carbon damage. Repair or replace faulty wiring or components as needed, then recheck the throttle body and TPS.
Connect the scanner to the diagnostic connector; retrieve all stored fault codes and note them for future reference. I also keep all associated freeze frame data. My notes are often helpful if the stored code proves to be intermittent. Then I would clear the codes and test the vehicle. Continue diagnosis if the code resets. If it doesn’t reset, the condition may need to worsen before a proper diagnosis can be made. Drive the vehicle normally until the PCM enters readiness mode or the code resets.
Proceed by checking the Technical Service Bulletins (TSBs) that apply to the specific malfunction (and vehicle) in question by consulting your vehicle information source. If applicable, use the information in the appropriate TSB to assist in your diagnosis. TSBs can be particularly helpful when diagnosing an intermittent condition.
The scanner data stream can provide useful information regarding faults and inconsistencies in the throttle position sensor. If you filter the scanner data stream to display only relevant data, you’ll get a more accurate response from the data.
If no issues are detected, use the DVOM to test the TPS. Using the DVOM gives you access to live data if the appropriate test leads are connected to the ground and signal circuits. Watch the DVOM screen while manually operating the throttle. Look for voltage spikes when the throttle is slowly operated from closed position to wide open throttle. Voltage typically ranges from 0.5 volts at closed throttle to 4.5 volts at open throttle. If faults or other inconsistencies are detected, suspect that the tested sensor is faulty or improperly adjusted.
Additional Diagnostic Notes:
If the TPS has been replaced and a P2124 continues to be stored, consult the vehicle information source for TPS adjustment specifications
Use the DVOM (with test leads connected to ground and signal circuits) to accurately adjust the TPS