What does P0122 mean?
The throttle position sensor (TPS) tells the computer how far the throttle is open. On electronic throttle systems there are two TPS signals that must agree with each other and with the accelerator pedal sensors.
The computer is seeing a signal voltage that is lower than the sensor should ever produce, so it is almost always an electrical problem rather than a mechanical one.
Codes are a starting point. They tell you which test failed, not which part to replace. Check for other stored codes and fix those in a sensible order.
Symptoms
- Check engine light
- Reduced power or limp mode
- Hesitation or surging
- Erratic idle
- Shifting problems on automatics
Common causes
- Open in the 5 V reference wire
- Signal wire shorted to ground
- Unplugged or corroded connector
- Failed sensor
How to diagnose P0122
- With the key on, back-probe the connector: you should see about 5 V on the reference wire and a good ground (under 0.1 V drop).
- If reference and ground are good, check the signal wire for a short to ground with the connector unplugged.
- If the wiring checks out, the sensor itself is the likely fault.
- Watch TPS voltage in live data while slowly pressing the pedal (key on, engine off). It should move smoothly with no dropouts.
- Check the throttle body for carbon buildup.
How to fix it
- Clean the throttle body (then do the idle relearn if needed)
- Repair wiring
- Replace the TPS or throttle body
Estimated repair cost
Likely repairs for P0122 run from about $100 to $900, depending on the cause.
| Repair | Typical range (parts + labor) |
|---|---|
| Diagnostic fee (scan + testing) | $100 - $200 |
| Throttle position sensor | $100 - $300 |
| Electronic throttle body replacement | $300 - $900 |
These are rough US estimates for an independent shop in 2026, based on typical parts prices and standard labor times. Dealers, big trucks, luxury brands and high-cost areas often run higher. They are not quotes. Use the repair cost estimator to adjust for your vehicle.
How serious is P0122?
High severity
Limp mode can limit speed, so plan to fix it soon. Sudden loss of power in traffic is a safety risk.
P0122 FAQ
What does P0122 mean?
P0122 stands for "Throttle/Pedal Position Sensor/Switch "A" Circuit Low". The throttle position sensor (TPS) tells the computer how far the throttle is open.
Can I drive with a P0122 code?
Limp mode can limit speed, so plan to fix it soon. Sudden loss of power in traffic is a safety risk.
How much does it cost to fix P0122?
It depends on the cause. The likely repairs for P0122 range from about $100 to $900 at an independent shop in the US, plus a diagnostic fee of roughly $100-$200. These are rough estimates; dealer prices and some vehicles run higher.
What is the most common cause of P0122?
The most common causes are: open in the 5 V reference wire; signal wire shorted to ground; unplugged or corroded connector.