What does this code mean?
A sensor tells the car the throttle or pedal position. P0122 means electrical signal A is too low. This describes information reaching the car computer, not how gently you are pressing the pedal.
Locate the reported problem
An affected supply, ground, connector or signal circuit can resemble a sensor failure. Other reference-voltage faults can help establish whether the problem is shared.
Read it with the other codes
P0121 concerns plausibility; P0122 concerns the low signal limit. Replacing the pedal or throttle without identifying the affected circuit can miss the cause.
Possible causes to investigate
These are possibilities, not a diagnosis or a ranked list of failed parts.
- An unreliable position signal caused by a connector, wiring, reference supply or sensor.
- A disagreement between position tracks or a throttle assembly problem requiring vehicle-specific checks.
What to do first
- Record reduced-power messages and whether accelerator response changed. Note recent battery, pedal or throttle work.
- Do not force an electronic throttle plate or probe connectors with improvised tools. If acceleration is unpredictable, stop safely and arrange help.
What the workshop can check
Identify the affected sensor and compare position tracks, supply and grounds using the correct wiring and diagnostic procedure. The generic throttle/pedal label does not establish which assembly must be replaced.
A useful question to ask
What pulls signal A low, and was the shared sensor supply checked?
Your vehicle changes the next step
Year, make, model, engine and the complete code list matter. Cylinder layout, test conditions and repair procedures can differ. Use service information for the exact vehicle; a generic code does not establish an exact failed part.
Can I keep driving?
This page cannot decide whether your car is safe to drive. A flashing engine light, severe shaking, overheating, strong fuel smell or major power loss calls for prompt attention. Stop safely when needed, follow your handbook and seek assistance rather than continuing a test drive.
Terms in this guide
These words appear in the explanation. Select an underlined term in the text to reach its definition.
- Sensor and signal
- A sensor measures something such as pressure or temperature. Its signal carries that information electrically to the car computer; a wrong reading does not always mean the measured component is faulty.
- Throttle plate and throttle body
- The throttle plate is a flap controlling air entering the engine. The throttle body contains it; it is separate from the accelerator pedal you press.
- Circuit, supply and ground
- A circuit includes the wiring and connections carrying electricity. Supply powers a component; ground is its electrical return. A fault in any of these can change a reading.
- Control unit
- A car computer that receives measurements and controls the engine or another system. It may also be called a module, ECU, ECM or PCM.
- Voltage
- The electrical difference that drives current, measured in volts. In a sensor code, high or low may describe this signal rather than the real temperature or pressure.
Sources and scope
Definitions and general OBD context are cross-checked against the references below. Manufacturer documents describe specific vehicles and systems; their procedures and thresholds are not instructions for every make. This is educational guidance, not a vehicle-specific repair procedure.