P215C: Output Shaft Speed - Wheel Speed Correlation
What to do
Check whether all four tyres match — same size, same make, and similar tread depth. On a four-wheel-drive vehicle this genuinely matters: different rolling circumferences make the axles work against each other, which is what this fault detects and which damages the transfer case if it is left.
Mention a space-saver spare, or a single tyre replaced recently, since either can be enough to cause this.
Say whether the fault appears under acceleration or load rather than at steady speed. That pattern suggests something in the driveline slipping rather than a sensor, which is a different and more important finding.
Mention any vibration, binding on tight turns, or noise from underneath, which support a driveline cause.
What this code means
The transmission output shaft speed and the wheel speed sensors do not agree.
This is the more direct of the two correlation checks, comparing the gearbox output against the wheels themselves rather than against a derived vehicle speed. Between them there is only the final drive and the tyres, so the arithmetic is simple and a disagreement is meaningful.
Which makes the causes shorter and more physical than its sibling's.
- Mismatched tyres, front to rear or side to side. On a four-wheel-drive vehicle this matters more than most owners realise — different rolling circumferences make the axles fight each other, which this check notices and which also damages the transfer case over time.
- A wheel speed sensor or its tone ring, where a cracked reluctor gives an erratic count.
- The output speed sensor itself.
There is one mechanical cause worth naming because it is not a sensor at all. On a four-wheel-drive vehicle, a slipping clutch pack or viscous coupling lets the driven wheels turn at a different rate from the gearbox output — the sensors are all correct and the driveline is slipping. A check that keeps failing under load but passes on a steady cruise fits that.
Ask what tyres are fitted and whether they match, before anything is measured. A single replacement tyre of a different make or wear state is enough on some vehicles, and it is free to establish.
Likely causes
Start here
- Mismatched or incorrectly sized tyres · moderate
- Faulty wheel speed sensor · moderate
- Damaged reluctor or tone ring · moderate
Less common
- Faulty output speed sensor · moderate
- Slipping four-wheel drive clutch pack · specialist
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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