Throttle/Pedal Position Sensor/Switch A Circuit Low Input
This code indicates that the throttle position sensor is sending a low voltage signal.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The computer is getting a signal from the throttle position sensor that is too low, which usually means there's an issue with the sensor, its wiring, or the connector.
What the computer is actually seeing
The engine control module (ECM) expects a voltage between 0.5V and 4.5V from the throttle position sensor. When the voltage drops below 0.2V or remains near 0V, this fault code will trigger.
What a healthy reading looks like
Expected voltage at the throttle position sensor should be around 0.5V (closed throttle) to 4.5V (wide open throttle).
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Inspect the wiring and connectors of the throttle position sensor for damage, corrosion, or loose connections. If everything is secure and intact, proceed to step 2.
- 22. Using a multimeter, measure the voltage at the throttle position sensor connector. Check for values between 0.5V and 4.5V. If voltage is too low or absent, replace the sensor. If voltage is correct, go to step 3.
- 33. Inspect the accelerator pedal position sensor wiring and connections. Look for the same issues as step 1. If they are good, proceed to step 4.
- 44. Check the ECM for any software updates or faults. If updates are available, apply them. If all else fails, replacement of the ECM may be necessary.
Common causes
- Faulty throttle position sensor
- Damaged wiring or connectors
- Poor electrical connections
- Faulty accelerator pedal position sensor
- ECM software issues
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Driving with a P2122 code can lead to reduced engine performance, so it's best to address it promptly.
Will this code come back after clearing it?
If the underlying issue isn't resolved, the code will likely reappear after clearing.
Why does it pair with codes like P2121 or P2135?
These codes are related to throttle position sensors and usually indicate multiple failure points in the throttle control system.
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