P0122: Throttle position sensor circuit low input
Drive carefully. Get it checked within a week or two.
Can I drive with P0122?
Yes, but drive carefully and get it checked soon. Throttle voltage drops below minimum spec, triggering reduced engine power and delayed throttle response.
What does P0122 mean?
P0122 stands for Throttle/Pedal Position Sensor/Switch 'A' Circuit Low Input.
Symptoms you may notice
- Sudden 'Reduced Engine Power' warning on dashboard
- Gas pedal feels dead or vehicle will not accelerate past 25-30 mph
- Jerky throttle response and abrupt engine surging
How much does it cost to fix?
Repair costs for code P0122 depend on the specific underlying root cause, ranging from simple DIY checks to component replacement. The table below lists the most common causes and rough price ranges in USD:
- Short to ground on TPS signal wire
- Defective throttle position sensor
- Broken 5V reference supply wire
- Poor ground connection at throttle housing
What to do next
- Check for 5.0 volts reference power and solid ground at the sensor connector.
- Verify that signal voltage increases smoothly from roughly 0.5V at idle to 4.5V at full throttle.
- Replace the TPS or throttle assembly if reference power is present.
Last updated: October 2026
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General guidance only, not a professional diagnosis. If the check-engine light is flashing, or the car is running rough, overheating or losing power, stop driving and get help.
About this code
P0122 indicates the throttle position signal voltage has dropped below 0.17 volts. The engine management system suspects an open or shorted sensor wire and limits vehicle acceleration to prevent runaway throttle events. Inspection of the wiring plug and replacing the TPS sensor cures the condition.