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DTC codes / U03xx · Software and configuration mismatches / U0336

U0336Software Incompatibility With Restraints Control Module

U0336 is a network communication code indicating that a control module on the vehicle's data bus has detected a software incompatibility with the Restraints Control Module (RCM), the computer that manages airbags, seatbelt pretensioners, and crash sensors. The code means the modules cannot agree on a compatible software version or configuration, not that a crash sensor or airbag circuit has failed.

SystemNetwork
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyProfessional
AreaSoftware and configuration mismatches

Symptoms you may notice

  • Airbag or Supplemental Restraint System (SRS) warning light illuminated on the dashboard
  • A message on the driver information display stating that the restraint system is unavailable or needs service
  • Other unrelated warning lights, such as stability control or traction control, may appear if the network is disrupted
  • Intermittent warning light behavior, sometimes clearing after a restart and returning later
  • Often no symptoms besides the warning light, with the vehicle driving normally

Common causes, most likely first

  1. A control module was replaced or reprogrammed with software that does not match the Restraints Control Module's configuration
  2. The Restraints Control Module itself was replaced with a used or incorrect unit that carries incompatible software
  3. A software update was performed on one module without the corresponding update to the Restraints Control Module
  4. Corrupted or incomplete module configuration data stored during a previous repair or battery disconnect
  5. A wiring or connector fault on the Controller Area Network (CAN) bus that corrupts messages between modules
  6. Low battery voltage or a poor ground causing modules to boot with incomplete software handshakes
  7. A failing Restraints Control Module that cannot complete its software compatibility check

How to diagnose and fix it

  1. Verify battery voltage and condition, and check that the battery is fully charged before any module diagnosis
  2. Scan all modules for codes and record every stored and pending code, paying attention to any U-codes beyond U0336
  3. Inspect the CAN bus wiring and connectors at the Restraints Control Module and at any recently serviced module for damage or corrosion
  4. Check service records for recent module replacement, reprogramming, or software updates that could explain the mismatch
  5. Use a factory-level scan tool to read the software part numbers and configuration data of the Restraints Control Module and compare them with the vehicle's expected values
  6. Perform the manufacturer's module configuration or software alignment procedure, reprogramming the affected module with the correct software
  7. If configuration cannot be completed, replace the Restraints Control Module with a correct unit and perform the required programming and calibration

Why U0336 Often Follows a Module Replacement

  • This code is frequently set after a body control module, instrument cluster, or other network module is replaced with a used unit that carries software from a different vehicle configuration.
  • A weak or failing battery can cause modules to boot with incomplete software handshakes, setting U0336 even though no hardware has been changed.
  • Technicians sometimes replace the Restraints Control Module when the real fault is a mismatched software version in another module, so reading software part numbers before condemning parts is essential.
  • U0336 can appear alongside other U-codes when a single module on the bus is disrupting communication, so the full code list matters more than this code alone.
  • The code does not necessarily mean the airbags are disabled; some vehicles keep the restraint system functional while logging the incompatibility, but the warning light should never be ignored.

Can I keep driving with U0336?

The vehicle is generally safe to drive to a repair facility because the restraint system may still function, but do not ignore the warning light and avoid any situation where airbag deployment could be expected until the fault is corrected. If the airbag light is accompanied by other network warnings or the engine runs poorly, have the vehicle towed rather than driven.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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