U0125: Lost Communication With Multi-axis Acceleration Sensor Module A
What to do
Expect a stability control warning; the car will otherwise drive normally, with the same reduced protection described at U0122.
If several sensor codes are stored together, that is usually one part. Modern vehicles put yaw rate and the acceleration sensors in a single small module, so codes naming them separately typically point at one connector.
One thing to insist on if the module is replaced: that it is calibrated afterwards. These sensors only mean anything if the car knows which way round they are fitted, and an uncalibrated one reports believable numbers about the wrong axis — which is worse than no sensor, because the system acts on them.
Mention any water in the footwells or a leaking screen or sunroof seal; the module usually sits low in the middle of the car and that is a common cause.
What this code means
The multi-axis acceleration sensor module has stopped being heard from. The general reasoning is at U0100.
This code exists because the separate sensors described at U0123 and U0124 were combined into one package, and it is the arrangement most vehicles now use. A single module measures yaw, lateral acceleration and longitudinal acceleration — and on vehicles with roll-over protection, roll rate as well — because the sensing elements are small, cheap and best kept together at a known point on the vehicle.
Two consequences follow from that packaging, and both save time.
- One fault produces several codes. A vehicle storing this alongside U0123 and U0124 is describing one module, not three, and the presence of all of them is a strong argument for the connector rather than for the sensors.
- Orientation matters. A combined sensor only means anything if the vehicle knows which way it is fitted, so these modules must be installed the correct way round and calibrated after replacement. A module that is fitted but not calibrated reports plausible values in the wrong axes, and stability control will act on them.
Mounted low and centrally, so the water ingress point at U0123 applies here too.
Likely causes
Start here
- Corroded or loose connector · easy
- Water ingress into connector · moderate
- Damaged data bus wiring · moderate
Less common
- Sensor not calibrated after replacement · specialist
- Faulty yaw rate sensor · moderate
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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