Throttle/Pedal Position Sensor/Switch B Circuit Malfunction
There’s a problem with the circuit for the throttle or pedal position sensor B.
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 throttle position sensor B tells the engine computer how far the gas pedal is pressed. If the signal isn’t right, the computer can’t manage the engine performance properly.
What the computer is actually seeing
The engine control module (ECM) expects a voltage signal between 0.5V (pedal not pressed) and 4.5V (pedal fully pressed) from the throttle position sensor B. If the voltage is out of this range or missing, a fault code is triggered.
What a healthy reading looks like
0.5V to 4.5V based on pedal position; expected resistance for the sensor should be between 1000 to 5000 ohms when measured.
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.
- 1Check the wiring and connectors for any visible damage or corrosion for the throttle position sensor B circuit.
- 2Using a multimeter, check for voltage at the throttle position sensor B while operating the accelerator pedal. You should see a smooth change from 0.5V to 4.5V.
- 3If the voltage is incorrect, check the resistance of the throttle position sensor B; it should range between 1000 to 5000 ohms. If not, replace the sensor.
- 4If wiring and sensor check out, scan the vehicle for other fault codes. If multiple throttle-related codes exist, focus on the engine control module for potential issues.
Common causes
- Wiring issues (broken or shorted wires)
- Bad throttle position sensor
- Corroded connectors
- ECM fault
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's drivable, but performance may be affected, and you should fix it soon to avoid further issues.
Will this problem come back after clearing the code?
If the underlying issue isn’t fixed, the code will likely return.
Why does this code sometimes pair with P0121?
P0121 relates to the throttle position sensor A, indicating a broader issue with the throttle control system.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
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