Does a steering angle sensor need calibrating after wheel alignment?

Almost always, and forgetting it is one of the most common reasons this code appears. The sensor reports the angle relative to a stored straight-ahead position. Adjusting the tracking changes where the wheel physically sits when the car travels straight, so the stored centre point is no longer correct. The modules then find the steering reporting an angle while the car goes straight, and reject the reading. Most cars need a scan tool procedure to reset the centre; a few learn it by driving straight for a short distance.

Can a battery disconnection cause C0051?

On some cars, yes. The centre position and the sensor's learned values are stored in a module, and on certain vehicles that data is lost when power is removed. The car then has no reference for straight ahead until the calibration is run again or, on some models, until it has been driven in a straight line for a short distance. If the code appeared immediately after a battery change or a period with the battery disconnected, mention that, because it points straight at a calibration rather than a component.

Will a power steering fault fail an MOT?

Yes. An electric power steering warning lamp indicating a malfunction is a major defect, with 205 recorded failures in the DVSA data behind this site. That figure is low only because relatively few cars fitted with electric steering have reached the age where this shows up in volume. If the fault has also lit the stability control lamp, that is a separate major defect with 35,322 recorded failures. The tester also checks steering play and component condition directly.

Why does my steering feel heavier one way than the other?

Because the assistance is calculated from the steering angle and the direction of turn, among other inputs. If the angle sensor's centre point is wrong, the system applies assistance as though you are already turned one way when you are not, so turning in one direction gets more help than the other. It is a distinctive symptom and a useful one to describe to a garage, because it points at calibration rather than at a failed motor or pump.

Chassis code · standard

C0051Steering position sensor reading is not trusted

Standard definition: Power Steering Position Sensor Performance

Last updated 27 July 2026

Quick answer

The sensor that tells the car which way the steering wheel is pointing is producing a reading the system will not accept. Power steering assistance and stability control both rely on it, so both can be affected.

How the car works this out

The steering position sensor reports the wheel's angle and how fast it is being turned. The modules that use it — power steering, stability control and, on newer cars, lane keeping — cross-check that reading against the yaw rate sensor, the lateral acceleration sensor and the individual wheel speeds. If the car is turning but the steering says straight ahead, or the sensor's centre point does not match the direction the car actually travels, the reading is rejected. C0051 is set when that plausibility check fails. Crucially, this is often a calibration problem rather than a broken part, which is why the repair is sometimes nothing more than a procedure with a scan tool.

What you might notice

Power steering assistance feeling uneven, heavier in one direction than the other
Steering that does not self-centre properly after a turn
Stability control and traction control lamps on
Power steering lamp on
Lane keeping assist unavailable
Assistance dropping out and returning, sometimes after a restart

What causes it

Most likely first. A code names the check that failed, not the part that failed it, so more than one of these can produce the same number.

1A calibration lost after wheel alignment, steering rack replacement, suspension work or a battery disconnectionCommon
How to check: Ask whether the sensor has been recalibrated since the last work on the steering or suspension. On many cars this is a five-minute scan tool procedure and the whole answer.
2A failed sensor, often integrated into the clock spring assembly behind the steering wheelCommon
How to check: Check whether the airbag lamp is also on. If the sensor shares an assembly with the clock spring, one failure can produce both, which changes what needs replacing.
3A corroded or disturbed connector at the base of the steering columnPossible
4Worn steering components letting the actual geometry drift from what the sensor reportsPossible
How to check: Have the steering checked for play at the rack, track rod ends and column. Excessive play is a separate MOT defect as well.
5Non-standard wheels, tyres or a modified ride height changing the relationship between steering angle and the car's behaviourLess common
6A fault in the module reading the sensorLess common

What to do about it

1Ask for the calibration to be run first. If the car has recently had alignment, suspension, steering or battery work, a lost calibration is the likeliest explanation and it costs a fraction of a sensor.
2Have the steering checked for play while the car is up. Wear in the rack or track rod ends causes this code and is separately a defect at MOT time.
3Check whether the airbag lamp is also lit, which suggests the clock spring assembly rather than a standalone sensor.
4Mention any recent tyre, wheel or suspension changes, which can put the sensor's reading out of step with how the car actually behaves.
5Have it seen to rather than tolerated. Uneven power steering assistance is unpleasant in normal driving and unhelpful in an emergency manoeuvre.

Can you keep driving?

Only to a garage

The mechanical steering is unaffected — the wheel is still connected to the road wheels and the car goes where you point it. What can change is how the assistance behaves, and steering that is heavier one way than the other, or that does not self-centre, is genuinely distracting. Stability control is likely to be disabled as well, which matters most on wet or slippery roads.

Will it fail an MOT?

Two lamps to watch, both major defects. Electric power steering showing a malfunction is a major defect, recorded 205 times in the DVSA data behind this site — a small number only because comparatively few cars with electric steering are old enough to need an MOT, and one that will grow. A stability control lamp indicating a malfunction is a major defect with 35,322 recorded failures. Separately, the tester assesses steering play and the condition of the steering components by hand, so any wear that caused the sensor to drift out of tolerance may be recorded too.

The light this turns on

Power steering warning lightThe power steering system has reported a fault and the assistance may be reduced or switched off entirely. You have not lost steering — there is still a mechanical link from the wheel to the road wheels — but the car will feel heavy, and heaviest of all at parking speeds where you need the help most.

Common questions

Does a steering angle sensor need calibrating after wheel alignment?: Almost always, and forgetting it is one of the most common reasons this code appears. The sensor reports the angle relative to a stored straight-ahead position. Adjusting the tracking changes where the wheel physically sits when the car travels straight, so the stored centre point is no longer correct. The modules then find the steering reporting an angle while the car goes straight, and reject the reading. Most cars need a scan tool procedure to reset the centre; a few learn it by driving straight for a short distance.
Can a battery disconnection cause C0051?: On some cars, yes. The centre position and the sensor's learned values are stored in a module, and on certain vehicles that data is lost when power is removed. The car then has no reference for straight ahead until the calibration is run again or, on some models, until it has been driven in a straight line for a short distance. If the code appeared immediately after a battery change or a period with the battery disconnected, mention that, because it points straight at a calibration rather than a component.
Will a power steering fault fail an MOT?: Yes. An electric power steering warning lamp indicating a malfunction is a major defect, with 205 recorded failures in the DVSA data behind this site. That figure is low only because relatively few cars fitted with electric steering have reached the age where this shows up in volume. If the fault has also lit the stability control lamp, that is a separate major defect with 35,322 recorded failures. The tester also checks steering play and component condition directly.
Why does my steering feel heavier one way than the other?: Because the assistance is calculated from the steering angle and the direction of turn, among other inputs. If the angle sensor's centre point is wrong, the system applies assistance as though you are already turned one way when you are not, so turning in one direction gets more help than the other. It is a distinctive symptom and a useful one to describe to a garage, because it points at calibration rather than at a failed motor or pump.

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