U0402 code meaning
Invalid Data Received From TCM
Network system Generic code U04xx codes Check engine light
What U0402 means
U0402 is the reverse case of U0401: the engine controller or another listener receives the transmission controller's frames but rejects their content. GM's 2025 ECM checks counter, protection value and checksum of the estimated-gear and general transmission information signals, flags a fault at 8 errors among 18 checks, Type A after one trip; the body controller uses 15 of 16 and Type B. Saab's 2011 list names sub-codes 72 (counter), 73 (parity) and 74 (checksum). On the 2022 Ram 1500 5.7 L eTorque the PCM, once U0402 is set, refuses torque requests from the TCM, the gearbox falls into a fixed limp gear and the MIL lights; PCM software (18-001-23) cures it. On 2014-2015 Cherokee and 200 nine-speeds FCA traced U0402 and a rough 5-4 downshift to the C-clutch snap ring (21-008-15). U0101 is lost contact.
U0402 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor0.3 to 8 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0402
- Check engine light
- Transmission stuck in a fixed gear (limp mode)
- Harsh or delayed shifts
Common causes of U0402
- Most likelySoftware of PCM or TCM (update available)
- PossibleInternal transmission fault making the TCM send implausible values
- PossibleDisturbed CAN traffic from connectors, wiring or low voltage
- Less likelyTransmission control module internally faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
TCMCAN bus wiring
What each part of U0402 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 02 | The exact fault in that area. |
What to do next
- Note U0402 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U0402
What does U0402 mean?
U0402 means "Invalid Data Received From TCM". U0402 is the reverse case of U0401: the engine controller or another listener receives the transmission controller's frames but rejects their content. It is a generic code, so it means the same on every make.
Is it safe to drive with U0402?
Drive gently and only to a workshop. With U0402 the car can go into limp mode (reduced power) to protect itself.
Will U0402 fail an emissions test?
Yes, it can. U0402 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is U0402 to fix?
Difficulty: hard. A typical repair takes 0.3 to 8 hours of work. This is a job for a workshop.
Will U0402 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.