P0223 Code: Throttle/Pedal Position Sensor/Switch B Circuit High Input

What the P0223 code means

The electronic throttle system carries 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 P0223 code is stored when the sensor B signal goes above the expected maximum, typically above 4.8 volts for a sustained period. No real position produces that value.

The two electrical causes that explain it are a signal wire shorted to a voltage line and an open sensor ground. The second deserves attention because it is less obvious: with no ground, the internal circuit of the sensor cannot pull the voltage down and the signal runs to the maximum even though the component is intact.

The system response is the usual one whenever there is any doubt about the throttle. Even if signal A keeps arriving fine, the computer cannot verify it and so it does not trust it: it closes the throttle to a minimum opening and limits the engine.

It helps to understand why the manufacturer designs the sensor so its signal never reaches the end of the scale. If wide open it delivered the full five volts, a short to the supply line would produce exactly the same reading and the computer could not tell a throttle pressed to the floor from a shorted wire. Leaving a margin of about three tenths of a volt at the top end settles that ambiguity: any value above it can only mean an electrical fault. It is the same principle, applied at the top, that explains why the signal does not drop to zero at rest either.

It is worth knowing a check that isolates the sensor ground in under a minute. With the sensor plugged in and the key on, measure the voltage between the sensor ground pin and the battery ground: it should be practically zero. Any noticeable value means that ground has resistance, and that is why the signal runs up to the maximum.

It is a more reliable measurement than checking continuity, because a ground can show continuity and still have enough resistance to upset the signal when current flows.

P0223 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 maximum on the scan tool.
• Erratic shifting on automatic transmissions.
• Other sensors in the same group set codes at the same time if the ground is shared.

Likely causes of the P0223 code

1. Sensor ground open or with high resistance. It runs the signal up to the maximum with the sensor intact.
2. Signal wire shorted to a voltage line.
3. Connector with moisture or conductive residue between pins.
4. Sensor failed internally.
5. Wiring rubbed against a power line.
6. Backed-out pins in the connector.
7. Liquid getting in on the sensor or around the pedal.
8. Damaged input stage in the computer. Uncommon.

How to diagnose the P0223 code step by step

1. Watch both signals in live data. If one reads maximum with the pedal untouched, the fault is electrical and narrowed to that circuit.
2. Check the sensor ground by measuring its voltage drop. It is the cause that gets the most sensors replaced for no reason.
3. Unplug the sensor and watch the reading. If the high voltage stays, the problem is in the wiring.
4. Look for shorts between the signal wire and the supply lines.
5. Inspect the connector for moisture and conductive residue between pins.
6. Move the harness with the key on while watching the reading.
7. Find out whether there were spills or a recent wash in the area.
8. Check for more sensor codes, because the ground is often shared.
9. Measure the voltage between the sensor ground pin and the battery ground with the circuit active: it should be practically zero. It is more reliable than checking continuity.

How to fix the P0223 code

• Repair the sensor ground down to bare metal, checking that its voltage drop ends up below 0.2 volts.
• Correct the short on the signal wire and protect the repaired section.
• Dry and clean the connector and protect it with dielectric grease.
• Replace terminals with backed-out pins.
• Replace the sensor if the circuit checks out and it still gives an impossible signal.
• Protect the wiring so it cannot rub again.
• Repair the ground if the measurement under load shows a noticeable voltage, even if the continuity test comes out fine.

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. Wide open: between 3.8 and 4.7 volts.
• Threshold that sets the code: above 4.8 volts for a sustained period.
• An open ground runs the signal up to the maximum even though the sensor is intact.
• Allowable voltage drop on the ground: below 0.2 volts.
• P0222 is the opposite code: signal too low.
• P0221 means the signal is valid but its behavior is wrong.
• A ground can show continuity and still have enough resistance to upset the signal when current flows.

Brand-specific notes

An open ground is the cause that gets the most sensors replaced for no reason with this code. Measure its voltage drop before you decide: if it is high, the sensor is perfectly fine and the problem is in the wiring.

Also check whether there are more sensor codes. Ground and reference are often shared, and a single corroded point sets several codes that look like independent faults.

Frequently asked questions about P0223