P0122 means Throttle/Pedal Position Sensor/Switch A Circuit Low Input. The throttle position sensor A signal voltage is lower than possible, usually an open circuit or short to ground. It is a generic OBD-II code, so the definition is the same on any make, but the most likely cause varies by engine; confirm with a scan tool and the service information for your vehicle before buying parts.
What P0122 means
Most vehicles built in the last two decades use electronic throttle control instead of a throttle cable: the accelerator pedal carries two or three position sensors, and the throttle body has a motor and two position sensors of its own. The computer compares the redundant sensors constantly, and any disagreement triggers reduced-power mode as a safety measure. Older engines with a throttle cable control idle with a separate idle air control valve.
P0122 symptoms
- Reduced-power mode
- Stalling or poor throttle response
- Harsh or delayed shifting
Common causes of P0122
- Open in the 5-volt reference or signal wire
- Short to ground
- Failed sensor or throttle body
How to diagnose P0122
- Check the connector and wiring
- Check reference voltage and ground
- Watch the signal while moving the throttle
Can you drive with P0122?
Limited: the computer often restricts throttle opening. Repair soon.
P0122 tips
If several sensors that share a 5-volt reference set low-input codes together, the shared reference is shorted, often by one failed sensor. Unplug sensors one at a time to find the culprit.
Will P0122 clear itself?
If the fault stops, the computer turns off the check engine light by itself after several drive cycles without seeing it again, and the code stays in memory as history for a while. Clearing P0122 with a scan tool after a repair is fine, but if the cause is still there the code returns, sometimes within one drive. Disconnecting the battery also clears codes on most vehicles, but it erases learned fuel trims and idle settings as well.
Related codes
| Code | Meaning |
|---|---|
| P0121 | Throttle/Pedal Position Sensor/Switch A Circuit Range/Performance |
| P0123 | Throttle/Pedal Position Sensor/Switch A Circuit High Input |
| P2135 | Throttle/Pedal Position Sensor/Switch A/B Voltage Correlation |
Guides that help
When it is more than a sensor
Throttle and idle codes are fixed at the throttle body, the pedal, a sensor or a leak. If those check out and the engine still runs poorly, a compression test separates a control problem from a worn engine; compare engines by code on our engines page.
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