U0437: Invalid Data Received From Differential Control Module — Rear
What to do
What you have lost depends on what kind of vehicle you have, and both are worth knowing.
If it is an off-roader or a tow vehicle, you have lost traction on slippery surfaces — see U0436. Expect one wheel to spin where the car used to pull away cleanly, and do not rely on it in mud, wet grass or snow.
If it is a performance car, you have lost the system that helps it turn into corners. The car will run wider than you expect on a corner taken at your usual speed — so leave more margin until you have adjusted.
One thing worth asking about: has the rear differential been serviced recently? These units need a specific fluid, often with friction modifiers, and the wrong specification makes them behave differently and report figures that do not match what was asked for. That is a cheap thing to check and to correct.
If an ABS or steering angle fault is also stored, that is likely the real cause and this is a knock-on.
What this code means
The rear differential control module is broadcasting data that cannot be accepted as true. See U0436 for what a controlled differential does and why losing it costs more traction than expected.
A rear controlled differential is fitted for two quite different reasons, and which applies changes what the driver loses.
On an off-road vehicle it is a locking differential for traction, and everything at U0436 applies.
On a performance vehicle it is a torque-vectoring differential, and its purpose is handling rather than traction: by sending more torque to the outside rear wheel in a corner, it helps rotate the car into the turn. Losing that makes the vehicle understeer more than its driver expects — it will run wider on a corner taken at the usual speed, which is a handling change worth being ready for rather than discovering.
That distinction is worth establishing, because "the car understeers more" and "the car has no traction on grass" are both correct answers depending on the vehicle.
One consideration is specific to the rear axle and is worth checking before parts are considered: fluid. These differentials use specific fluids, often with friction modifiers, and a unit that has been serviced with the wrong specification behaves differently and can report values that do not match what is commanded. A vehicle with a recent differential service and this code is worth asking about.
And the standing input rule applies: the differential acts on wheel speeds and steering angle, so faults at U0415 or U0428 propagate here and are one problem rather than two.
Likely causes
Start here
- Water ingress into the module connector · moderate
- Corroded or loose connector · easy
- Damaged wiring harness · moderate
Less common
- Faulty four-wheel drive clutch control module · specialist
- Faulty wheel speed 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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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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