U0331 — Software Incompatibility With Body Control Module "A"

OA fault code doesn’t yet mean the unit or sensor itself is faulty: often it’s the plug and connector leading to it.

Possible causes

• The unit was replaced (new or from another car) but not coded to this car
• The unit’s part number or software version doesn’t match the car
• Reprogramming didn’t finish: the voltage dropped during it
• Less often, a fault in the unit itself

What you can do yourself

1. The body control module runs the lights, turn signals, wipers and locks, and on some cars it also authorizes starting. Check the lights, turn signals and wipers: if they don’t work, don’t drive in the dark or in the rain.
2. The body control module usually sits in the cabin — under the steering wheel, behind the glovebox or by the fuse box. Check the floor mat for water: a leak corrodes the unit’s connector.
3. The letter (A, B, C…) is the unit’s number for this make: a scan tool that reads all units or the wiring diagram will show which unit it is.
4. This code usually appears after a unit was replaced or reprogrammed. Think about what was replaced or reprogrammed.
5. Compare the labels on the old and new unit: part number, hardware (HW) and software (SW) numbers. If they don’t match, the unit may work incorrectly even if the car starts.
6. The unit is coded to the car with a scan tool that supports this make. Connect a battery charger while this is done: if the voltage drops, the programming fails.

On Oleg’s website:Car wiring repair ↗

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The explanation comes from the error code reference in the AvtoElektrik PRO app.