P0122 Code – Throttle Position Sensor Low Input

The P0122 code indicates that the Engine Control Unit (ECU) has detected a low voltage signal from the Throttle Position Sensor (TPS).

A low input signal means the ECU interprets the throttle as closed or near closed, even when the accelerator is pressed.

TPS operation:

• low throttle → low voltage

• high throttle → higher voltage

In this case, the ECU receives too little voltage, usually due to a short to ground or sensor failure.

Symptoms of Code P0122

Common symptoms include:

• Check Engine Light ON

• Poor acceleration

• Engine hesitation

• Limited throttle response

• Vehicle stuck in limp mode

• Rough idle

In severe cases, the vehicle may not respond properly to the accelerator.

Common Causes of P0122

Typical causes include:

• Faulty TPS sensor

• Short circuit to ground

• Damaged wiring

• Loose or corroded connectors

• Throttle body issues

• ECU fault (rare)

How Serious Is Code P0122

The P0122 code is considered moderate to serious.

It can cause:

• loss of power

• unsafe driving conditions

• poor throttle control

Immediate inspection is recommended.

How to Diagnose Code P0122

Diagnosis steps:

1. Scan vehicle with OBD2 scanner

2. Check TPS live data (may show very low voltage)

3. Inspect wiring for short to ground

4. Check sensor connector

5. Measure TPS voltage and resistance

6. Verify throttle movement response

How to Fix Code P0122

Possible solutions include:

• replace faulty TPS sensor

• repair shorted wiring

• clean or replace connectors

• inspect and clean throttle body

• recalibrate throttle system

• clear code after repair

Vehicles Commonly Affected

The P0122 trouble code may appear on:

• Volkswagen

• BMW

• Opel

• Ford

• Toyota

• Audi

• Mercedes-Benz

FAQ – P0122 Code

Can I drive with code P0122?

Driving is possible, but performance may be severely limited.

What does low input mean?

It means low voltage signal, usually caused by a short to ground.

Can this cause limp mode?

Yes, very commonly.

Conclusion

The P0122 code indicates a low voltage signal from the throttle position sensor, typically caused by wiring issues or sensor failure. Prompt repair restores proper throttle response.