U0123: Lost Communication With Yaw Rate Sensor Module
What to do
Expect the stability control warning lamp, and a car that otherwise drives normally. As at U0122, what has gone is protection that only operates when the car starts to slide — so allow more margin in poor conditions until it is fixed.
Two things worth mentioning to whoever looks at it. If codes for the lateral acceleration or multi-axis sensor are stored as well, that is usually one part rather than three — these sensors are normally packaged together in a single small module. And that module typically lives low down in the middle of the car, under the console or a seat, so if there has been any water in the footwells, a spilt drink, or a leaking screen or sunroof seal, say so. That is a common cause and it is easily missed.
What this code means
The yaw rate sensor module has stopped being heard from. The general reasoning is at U0100.
Yaw is rotation about the vertical axis — the car turning to face a different direction. The sensor measures how fast that is happening, in degrees per second, and it is the single most important input stability control has: it is what tells the system the car is actually rotating, as distinct from merely being steered.
The comparison it feeds is the whole of stability control. The steering angle sensor says how much the driver asked the car to rotate; this says how much it is rotating. Rotating less than asked is understeer; rotating more is oversteer, and the correction differs completely between the two — so without this measurement the system cannot tell which is happening and correctly refuses to act at all.
The practical consequence is therefore the same as U0122: stability control switches itself off, and the car drives normally until it does not.
One thing worth knowing before a part is quoted: on most vehicles this is not a sensor on its own. Yaw, lateral acceleration and often longitudinal acceleration are packaged together in one small module, usually mounted near the centre of the car under the console or a seat. So U0123, U0124 and U0125 appearing together are one part and one connector rather than three faults — and its location means a leaking screen seal, a spilt drink or a wet carpet is a genuine and frequently overlooked cause.
Likely causes
Start here
- Corroded or loose connector · easy
- Water ingress into connector · moderate
- Damaged data bus wiring · moderate
Less common
- Failed power or earth supply to the module · moderate
- Faulty yaw rate sensor · moderate
Symptoms
Components involved
Information, not instruction
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Community experience
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