OBD-II trouble code
U0336: Software Incompatibility With Restraints Control Module
A module has detected that the restraints control module (airbag control module) is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, but because this module governs airbag and seatbelt pretensioner deployment, it's treated as a high-priority, safety-relevant code.
Quick facts
- System
- Network
- Category
- Network Communication
- Severity
- High severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $150 – $650
- DIY difficulty
- Shop recommended
What does U0336 mean?
U0336 sets when a module on the vehicle network determines that the restraints control module — commonly called the airbag control module or RCM — is running a software or calibration version that is incompatible with the version-matched set the rest of the vehicle expects. The RCM continuously reads crash sensors, seatbelt buckle and pretensioner status, and occupant classification data to decide, in milliseconds, which airbags to deploy and how, in a collision. Because that decision logic must match the exact sensor and pretensioner hardware installed on the vehicle, manufacturers release RCM software as a tightly version-matched, VIN-specific calibration. When the RCM's software doesn't fit that set, U0336 is stored — the module is still communicating on the network, but its programming disagrees with what the rest of the vehicle expects it to be running.
The cause is almost always service-related and centered on the restraints control module. It was replaced (including with a used or salvage unit) and not programmed with the correct VIN-specific software, a software update was applied to other modules but not the RCM, a reflash was interrupted or used the wrong calibration file, or the vehicle's crash sensor/pretensioner configuration was changed (for example, front-end or seat repair work) without the RCM being reconfigured to match. Because the underlying issue is data rather than a failed sensor or wiring harness, chasing it electrically leads nowhere — the fix is reprogramming the RCM to a matching, manufacturer-approved software set, and confirming crash data/history logs are clear.
U0336 is rated high severity — not because the vehicle is undriveable, but because the restraints control module is a life-safety system. A software mismatch means the airbag warning light may stay on (a legal and safety signal that the system isn't guaranteed to function correctly), and there's genuine uncertainty about whether airbags, seatbelt pretensioners, and crash sensors will deploy correctly in the exact way this vehicle's occupant protection was engineered. Treat U0336 the same way you would any airbag warning light: do not delay diagnosis, and avoid transporting occupants (especially children in car seats) with the airbag light illuminated any longer than necessary to get it professionally diagnosed and corrected.
Common causes
- Restraints control module (RCM/airbag module) replaced without correct VIN-specific programming
- A used or salvage-yard RCM installed without being re-coded to this vehicle
- Software updated on other modules but the RCM's calibration left out of step
- An interrupted or incomplete RCM reflash
- Crash sensor, seatbelt pretensioner, or seat/occupant sensor hardware changed without the RCM being reconfigured to match
- Reprogramming done with the wrong calibration file for the vehicle's specific restraint system configuration
Symptoms
- Airbag/SRS warning light on and a stored U0336
- Warning light may be steady or flashing depending on the manufacturer
- No noticeable change to normal driving, steering, or braking
- Condition typically appears right after an RCM replacement, crash repair, seat service, or software update
- Some scan tools may be unable to fully communicate with the RCM until the mismatch is resolved
Diagnostic steps
- 1.Confirm the recent history — U0336 almost always follows an RCM replacement, crash/collision repair, seat or seatbelt service, or a software update; identify what was serviced.
- 2.Scan all modules and read the RCM's software/calibration part number; compare against the manufacturer's current approved set for the exact VIN and restraint configuration.
- 3.Check for stored crash/deployment history in the RCM that may need to be cleared or addressed as part of the repair.
- 4.Note any companion codes from crash sensors, seatbelt pretensioners, or occupant classification systems.
- 5.Verify the module was programmed with correct VIN-specific software matching the installed sensor and pretensioner hardware.
- 6.Reprogram/reflash the RCM to the matching, up-to-date calibration using a manufacturer-approved tool, then perform any required system initialization.
- 7.Clear the codes and confirm U0336 does not return and the airbag warning light stays off through a full key cycle.
Repair cost
$150 – $650
This is primarily a programming fix. Reprogramming the RCM typically runs $150-$350, and up to $650 when dealer-only calibrations, crash-data clearing, or reconfiguration after collision repair are involved. If the RCM was replaced with the wrong part or a unit with prior deployment history, sourcing a correct replacement module is the larger expense; U0336 itself is usually resolved by correct reprogramming. Never substitute a used RCM without verifying it has no prior deployment/crash history.
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DIY vs shop
Leave this one to a qualified shop. It typically involves emissions-critical components, refrigerant handling, or other work that requires manufacturer-grade tooling, training, or certification. DIY attempts often produce a more expensive problem than the original code.