OBD-II Error Code P0122: TPS Sensor A Low Input – How to Fix It

Medium 30-60 minutes Medium Severity Verified June 2026
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Error Code
P0122
Brand
OBD-II Generic
Product Type
automotive
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
30-60 minutes
Error code P0122 indicates that the Engine Control Module (ECM) has detected a low voltage signal from the Throttle Position Sensor (TPS) 'A'. This usually means the sensor is faulty, the wiring is damaged, or there is a poor electrical connection. Driving with this code may cause poor acceleration, rough idling, or stalling.
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Tools You'll Need

How to Fix Error Code P0122

  1. Safety First: Park and Disconnect

    Always disconnect the battery before working on any electrical components.

  2. Locate the Throttle Position Sensor

  3. Inspect the Wiring and Connector

  4. Test the TPS Voltage

    Be careful not to short the probes.

  5. Check the Reference Voltage

  6. Replace the TPS Sensor (If Necessary)

    Over-tightening can damage the new sensor.

  7. Reconnect and Clear the Code

Parts You May Need

Throttle Position Sensor
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Throttle Position Sensor
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Throttle Position Sensor
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Throttle Position Sensor
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When to Call a Professional

If you're not comfortable working with electrical components, or if after replacing the TPS the code returns, consult a professional mechanic. Also seek help if you suspect an ECM failure.

Frequently Asked Questions

Can I drive with a P0122 code?
It is not recommended. The engine may run poorly, stall, or have reduced power. It can also cause transmission shifting issues. Have it diagnosed as soon as possible.
How much does it cost to fix P0122?
A new TPS sensor costs between $20 and $100, and labor at a shop is typically $50-$150. DIY replacement saves labor costs.
Will cleaning the throttle body fix P0122?
Possibly, if the code is caused by carbon buildup interfering with the TPS signal. However, P0122 specifically indicates a low voltage input, so it's more likely a sensor or wiring issue.
What other codes are related to P0122?
Related codes include P0120 (TPS circuit malfunction), P0121 (TPS range/performance), P0123 (TPS high input), and P0220 (TPS/switch B circuit).
Can a bad TPS cause transmission problems?
Yes, the TPS signal is used by the transmission control module for shift timing. A faulty TPS can cause harsh shifts, delayed shifts, or slipping.

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