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U0402: Invalid data received from the transmission control module

Another module is receiving impossible or inconsistent data from the automatic gearbox ECU. Often a gearbox sensor, low voltage or software.

Code U0402 at a glance
CodeU0402
SystemCommunication network
GroupU04xx, Invalid data between control units
TypeGeneric: it means the same on every make
Can you keep driving?With care

What U0402 means

The automatic gearbox control unit shares data such as the gear engaged, lever position and shaft speeds over the network. This code is stored by another module, often the engine ECU, when those messages arrive with out-of-range values or errors. The gearbox unit usually has its own codes that explain the source.

Most common causes

  • A faulty gearbox sensor, such as a speed or selector position sensor
  • Low or unstable battery voltage
  • Loose, corroded or oily gearbox control unit connector
  • Damaged network wiring or interference
  • Gearbox control unit with the wrong software, for example after replacement
  • Faulty gearbox control unit

Symptoms

  • Engine or gearbox warning light on
  • Harsh shifts or gears not engaging
  • Gearbox stuck in one gear (limp mode)
  • Gear indicator showing odd information

Can you drive with U0402?

With care You can drive with care, but the gearbox may stick in one gear with little performance. Have it checked soon and avoid towing or pushing the car hard.

How to check it

Also read the codes in the gearbox control unit. With the reader, watch the engaged gear and gearbox oil temperature live if your car offers them; a frozen or impossible value helps pinpoint the sensor.

How to read and clear U0402 with Final OBD

Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see U0402 with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

U0402 is a generic code, so it means the same on any make, for example on Abarth, Alfa Romeo, Cupra, Jeep, Nissan, Škoda. See what Final OBD does on your car in makes and models.

What does code U0402 mean?

The automatic gearbox control unit shares data such as the gear engaged, lever position and shaft speeds over the network. This code is stored by another module, often the engine ECU, when those messages arrive with out-of-range values or errors. The gearbox unit usually has its own codes that explain the source.

Can you drive with U0402?

You can drive with care, but the gearbox may stick in one gear with little performance. Have it checked soon and avoid towing or pushing the car hard.

How do you clear U0402?

With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, U0402 comes back.