Error P0122 – how to fix?

Code Definition P0122

Throttle Pedal Position (TPS) sensor / switch (TPS) Circuit A low input

What does the code P0122 mean?

P0122 is a generic OBD-II code which indicates that the Engine Control Module (ECM) has noticed that the TPS sensor circuit A output voltage is below the expected sensor range.

What causes the P0122 code?

The TPS sensor circuit output A to the ECM has dropped below the specified voltage and is 0.2 volts or less.

What are the symptoms of the P0122 code?

• The ECM turns on the Check Engine light and enters safety mode, cutting power to the throttle actuator to bring the throttle to the open position approximately below 6 degrees.
• The ECM controls the fuel injection and the timing to control the engine speed.
• The vehicle may have been driven very slowly with limited throttle response.
• The engine may idle higher than normal and may not accelerate as well as it did before the ignition problems occurred.

Note: Symptoms are determined by the manufacturer’s ECM safety strategy for the vehicle during a fault and may vary by manufacturer and vehicle.

How does the mechanic diagnose the P0122 code?

• Scan and document received codes, and view data from frozen frames to see when a code was set.
• Clears OBD-II fault codes and retests the vehicle to see if the code has returned.
• Visually inspects all TPS connections and wiring for loose or damaged parts.
• Compare the data between TPS A and B circuits on the scanner and, if incorrect, perform the TPS troubleshooting tests as recommended by the manufacturer.
• Replace TPS if necessary, clear codes and perform road test.

The most common errors when diagnosing the P0122 code

• Failure to do a visual inspection first
• No codes are scanned, documented, cleared, or retested to verify faults
• Replacing the TPS sensor without indicating that it is the cause of the problem
• Failure to compare TPS A and B in specification before and after repair or replacement

How serious is the P0122 code?

Code P0122 will cause the engine ECM to go into safe mode, which will cause various driving problems such as no acceleration, high idle, jerking, limited speed or stalling depending on the manufacturer’s safety mode strategy.

What repairs can fix the code P0122?

1. Repair or replacement of the TPS connector
2. Repair wiring if necessary
3. Replace the TPS with a new sensor

Additional notes regarding code P0122

• P0122 can be accompanied by other TPS codes, so you may need to follow the manufacturer’s troubleshooting tests for each code you receive to resolve the problem.
• Most of the faults for P0122 include a damaged TPS sensor or a loose connector.
• All TPS codes will put the ECM into trouble mode; the driving symptoms will be more or less the same.