P0C18: Drive Motor B Position Sensor Not Learned
What to do
As P0C17 — ask for the learning routine before any part is reconsidered.
What this code means
The position sensor on drive motor B has not had its calibration learned.
The explanation — that the offset between sensor zero and rotor magnetic zero is measured on the vehicle rather than built in, and is invalidated by replacing the motor, inverter or sensor — is at P0C17. On motor B the symptom is usually reduced all-wheel-drive performance rather than a general flatness.
Likely causes
Start here
Less common
- Faulty motor position sensor · specialist
- Battery disconnected or module reprogrammed · easy
- Corroded or loose connector · easy
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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