P0222: Throttle/Pedal Position Sensor/Switch B Circuit Low Input

What it means

The B channel voltage is below the lower diagnostic threshold, suggesting an open circuit, short to ground, or sensor element failure on track B.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test
• The engine or gearbox may go into limp mode

How it works

The PCM monitors the signal voltage from throttle or accelerator-pedal position sensor B. P0222 sets when that signal falls below the circuit’s lower diagnostic threshold, indicating a low input but not identifying whether the cause is wiring, a connection, or the sensor itself.

Common causes

Most likely first.

1. TPS B circuit open or shorted to ground
2. Wiring or connector fault
3. Connector pins corroded - high contact resistance

Symptoms

• Check engine light on
• Reduced throttle response, possible limp mode
• Hesitation or surging
• Idle too high or too low

How to diagnose it

1. Record freeze-frame data and check for other sensor B or reference-voltage codes that may point to a shared circuit problem.
2. View sensor B live data while moving the pedal or throttle to confirm whether the reading stays low or changes intermittently.
3. Inspect the B sensor connector and harness for corroded pins, loose terminals, a wire shorted to ground, or damaged insulation.
4. Check the sensor B reference, ground, and signal circuit using the wiring diagram and manufacturer’s specification.
5. If wiring and connections pass inspection, test sensor B itself under the manufacturer’s diagnostic procedure.

Common fixes

• Clean and secure corroded or loose terminals at the sensor B connector.
• Repair an open or short to ground in the B signal circuit.
• Replace a failed throttle or pedal position sensor B if circuit testing confirms it.
• Repair a shared reference or ground fault if testing shows it affects the B circuit.

Can I keep driving?

Throttle response may be reduced or unpredictable, so avoid fast traffic and situations requiring prompt acceleration. Stop if the engine will not respond reliably to the pedal.