U0126: Lost Communication With Steering Angle Sensor Module
What to do
Expect a stability control warning, with the car otherwise driving normally and the reduced protection described at U0122.
Before anything else, say whether the car has recently had its tracking or alignment done, or any steering or suspension work, or the battery disconnected. This sensor measures the steering angle against a learned straight-ahead position, and all of those wipe it. Until it is recalibrated the car thinks you are turning when you are going straight — and recalibration is a few minutes with a scan tool rather than a part. A warning lamp that appeared right after a wheel alignment is this far more often than it is a fault.
If horn, steering wheel buttons or the airbag warning have also misbehaved, mention that too — they share the coiled cable that carries signals across the steering column, and one failure explains all of them.
What this code means
The steering angle sensor module has stopped being heard from. The general reasoning is at U0100.
Every other input to stability control measures what the car is doing. This one measures what the driver asked for, and the gap between the two is the entire basis on which the system acts. Without it there is nothing to compare against, so stability control disables itself.
The reason this code is worth reading carefully is that its commonest neighbour is not a fault at all.
A steering angle sensor reports angle relative to a learned straight-ahead position, and that learned zero is lost or invalidated by a great many ordinary jobs: a wheel alignment, a steering rack, a track rod end, a suspension strut, a steering column or clockspring, and on many vehicles simply disconnecting the battery. After any of those the sensor must be recalibrated, and until it is, the car believes it is being steered when it is going straight.
So a stability control or anti-lock warning that appeared immediately after having the tracking done is very often an uncalibrated steering angle sensor rather than a failure — and it is a scan tool procedure taking a few minutes, not a part. That is the same shape as the throttle relearn at P2176 and the transmission adaptations at P0949: not a broken component, an unfinished procedure read as one.
The genuine lost-communication causes are the family's usual ones, with one addition worth naming: the clockspring, the coiled flat cable that carries signals across the rotating steering column. It is a wearing part, it also carries the airbag and steering wheel controls, and when it fails those go together.
Likely causes
Start here
- Sensor not calibrated after replacement · easy
- Corroded or loose connector · easy
- Faulty steering column clockspring · moderate
- Damaged data bus wiring · moderate
Less common
- Failed power or earth supply to the module · moderate
- Faulty steering angle sensor · moderate
Symptoms
Components involved
Information, not instruction
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Community experience
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