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U0336 — Software Incompatibility Restraints Control Module

Generic OBD-II · all makesNetwork / communication

This code indicates that the vehicle's network has detected a software version mismatch or incompatibility with the Restraints Control Module (RCM), which manages the airbag system. It typically occurs after a module replacement without proper programming, or if an over-the-air or diagnostic software update was interrupted.

Symptoms

What causes it — most likely first

1. Unprogrammed replacement module

A used or new RCM was installed but not flashed or initialized with the correct software calibration for the specific vehicle.

2. Incomplete software update

A previous attempt to update the RCM software was interrupted or failed, leaving the module with incompatible or corrupted firmware.

3. Low system voltage during programming

Battery voltage dropped during a module flash or self-update, corrupting the software installation process.

4. CAN bus communication fault

Wiring or network issues are corrupting the data signals, causing the system to misinterpret the module's software version.

5. Faulty Restraints Control Module

The internal memory of the RCM has physically failed, preventing it from holding or executing the correct software.

How it's diagnosed

  1. Use an advanced diagnostic scan tool to read the RCM software version and verify the U0336 code along with any other network codes.
  2. Check for Technical Service Bulletins (TSBs) that mandate a specific software update or reprogramming procedure for the RCM.
  3. Inspect the vehicle's battery and charging system to ensure stable voltage, as low voltage can interrupt module programming.
  4. Attempt to reprogram or flash the RCM with the latest compatible software calibration using OEM-level diagnostic equipment.
  5. If programming fails, check the CAN bus wiring, module power, and ground circuits for faults before considering module replacement.

Code facts & related codes

SystemNetwork / communication
StandardizationSAE generic — identical on every make

Frequently asked

Is it safe to drive with a U0336 code?

No, it is not recommended. A software incompatibility in the restraints module means the airbags may not deploy correctly, or at all, in a crash.

Do I need to replace the airbag module or engine computer to fix this?

No, replacing the Restraints Control Module or PCM is almost never the correct fix for this code. It is a software issue, so the existing module typically just needs to be reprogrammed or flashed with the correct calibration.

Why did this code appear after replacing a battery or disconnecting it?

Some vehicles attempt module self-configurations or updates upon power restoration. If battery voltage is insufficient during this process, the software update can fail, triggering this incompatibility code.

Can a cheap scan tool fix this?

No, generic scan tools can only read and clear basic codes. Reprogramming the RCM requires an advanced, OEM-level diagnostic tool capable of flashing new software to the module.