B0290
Rear Defrost Switch Circuit
The body control module has detected a fault in the rear window defroster switch circuit. The switch may be stuck or its signal does not reach the module — the rear defroster cannot be activated.
- Check engine light: Not always
- Emissions related: No
- Repair difficulty: easy
Symptoms
- Warning light or symbol related to the affected system
- Comfort or safety function impaired
Common causes
Ordered by how often each turns out to be the cause.
- Defrost switch failedCommon
- Wiring or connector faultPossible
Parts involved
- Rear Defrost Switch
- Body Control Module
B0290 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.