U0402

Invalid Data Received From TCM

Car Fault Codes Network

Can you still drive? With care, short trips only

Who can fix it? Needs a workshop

Typical repair time 1 hour – 5 hours

Typical cost SAR 150 to 6,000

What it means

Another module, usually the engine computer (ECU) or the instrument cluster, is receiving messages from the transmission module (TCM) over the network, but their content is implausible or invalid, such as the shift lever position, current gear or shaft speed. The cause is usually in the transmission module, its sensors or its programming.

Symptoms4

Check engine light on.
Transmission in limp mode or harsh shifting.
Current gear or shift lever position not shown correctly on the cluster.
Cruise control or automatic start-stop disabled on some vehicles.

Possible causes5

A faulty transmission sensor, such as a speed sensor or the range switch, with its own code stored in the transmission module.
Incorrect programming or coding of the transmission module after replacement or an update.
Low battery voltage.
Intermittent fault in the network wiring or the transmission module connector, especially with oil or water intrusion.
Internal transmission module failure.

How to diagnose5

Read the transmission module codes first and fix any sensor or circuit codes there.
Watch live transmission data with a scan tool and compare it with the actual lever position and speed.
Measure battery and charging voltage.
Check whether the module was replaced or updated recently, and compare its version with the manufacturer specification.
Inspect the module connector for oil, water or corrosion, and check the network wiring.

How to fix6

Repair the sensor or circuit stored in the transmission module.
Charge or replace the battery.
Clean or repair the connector and fix the source of the leak.
Reprogram or recode the transmission module with the correct version.
Replace and program the module if proven faulty.
Clear the codes, road test and confirm the code does not return.

Repair cost

0–500

500–2,000

2,000–5,000

5,000+

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low for a sensor, connector or software update, and reaches the upper end if the transmission module must be replaced and programmed.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions

Does this code mean a mechanical transmission failure?

Usually not. It concerns the data sent by the transmission module, and the cause is normally a sensor, programming or wiring, but ignoring it can leave the transmission in limp mode.

Why is the code in the engine computer and not the transmission module?

The module receiving the data is the one that detects it is invalid, so it stores the code, while the cause is found in the transmission module.

This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.

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