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

What the P0222 code means

Electronic throttle systems carry two sensors at each measuring point. Sensor A is the main reference and sensor B exists to check it, so that no opening command is carried out without verification.

The P0222 code is stored when the sensor B signal falls below the expected minimum, typically below 0.2 volts for a sustained period. At rest that signal never reaches zero, precisely so the computer can tell a lifted foot from a cut circuit.

That points the diagnosis at the circuit: a signal wire that is cut or shorted to ground, a missing reference voltage or a sensor that is broken inside.

The system response is the usual one whenever there is any doubt about the throttle. Even if signal A keeps arriving correctly, the computer cannot verify it and so it does not trust it. It closes the throttle to a minimum opening and limits the engine, which is the only safe thing to do when redundancy is lost.

It helps to understand why the manufacturer always leaves half a volt of margin at rest. If a lifted pedal corresponded to zero volts, a cut wire would produce exactly the same reading and the computer would have no way of telling a driver with their foot off from a broken circuit. That margin settles the ambiguity: any value below it can only mean an electrical fault. It is the same principle almost every critical sensor on the vehicle follows.

A useful note on where this sensor can be. The letter B does not always refer to the pedal: on many systems sensors A and B are in the throttle body, while the pedal ones are identified with other letters such as D and E. Confirming which component the code refers to on your vehicle keeps you from removing the wrong one, because the symptoms are identical in both cases.

P0222 code symptoms

• Limp mode with very limited power.
• Check engine light on, along with the electronic throttle symbol.
• The engine does not respond to the pedal.
• Rough idle or an engine that stalls.
• Hard starting.
• One of the two signals reads zero on the scan tool.
• Erratic shifting on automatic transmissions.
• Identical symptoms whether the affected sensor is in the pedal or in the throttle body.

Likely causes of the P0222 code

1. Signal wire cut or shorted to ground.
2. Connector with backed-out, dirty or wet pins.
3. Five volt reference voltage missing.
4. Sensor failed internally.
5. Wiring rubbed along its route to the computer.
6. Sensor ground with high resistance.
7. Liquid getting in on the sensor or the pedal.
8. Damaged input stage in the computer. Uncommon.

How to diagnose the P0222 code step by step

1. Watch both signals in live data. If one reads zero and the other responds normally, the problem is narrowed to that circuit.
2. Check the reference voltage at the connector. If it is missing, see whether other sensors are affected too.
3. Measure the voltage on the signal wire with the sensor unplugged. If it stays at zero, the wire is cut or shorted to ground.
4. Rule out a short to ground with the computer connector unplugged.
5. Check the connector by unplugging it and plugging it back in firmly.
6. Check the sensor ground and its voltage drop.
7. Move the harness with the key on while watching the reading.
8. Find out whether there were spills or moisture in the area.
9. Confirm whether sensors A and B on your vehicle are in the pedal or in the throttle body. On many systems the pedal uses other letters, and removing the wrong component is a common mistake.

How to fix the P0222 code

• Repair the cut or grounded signal wire with solder and heat-shrink tubing.
• Restore the reference voltage by finding the short that is loading it down.
• Clean the connector and replace terminals with backed-out pins.
• Replace the sensor if the circuit checks out and it still gives no signal.
• Repair the sensor ground down to bare metal.
• Dry the area if liquid got in.
• Work on the component that really matches letters A and B on your vehicle, confirming it in the documentation.

After the repair, run the throttle relearn if the vehicle calls for it and check that both signals sweep their range in step with each other.

Technical reference data

• Typical sensor B signal at rest: between 0.5 and 0.9 volts, never zero.
• Threshold that sets the code: below 0.2 volts for a sustained period.
• Reference voltage: 5 volts, shared with other sensors on many systems.
• Allowable voltage drop on the ground: below 0.2 volts.
• P0223 is the opposite code: signal too high.
• P0221 means the signal is valid but its behavior is not what is expected.
• Letters A and B usually refer to the throttle body; the pedal is often identified with D and E.

Brand-specific notes

It helps to understand why the vehicle limits itself so much even though the main signal still arrives fine. The system does not accept working without verification: if it cannot check signal A against B, it prefers to trust neither. That logic explains a limitation that otherwise looks out of proportion.

Before you order the part, unplug the connector and plug it back in firmly. A connector that was not seated properly after work in the area explains a good share of the cases.

Frequently asked questions about P0222