C0301
Air Suspension Compressor Relay
The air suspension control module has detected a fault in the compressor relay circuit. The compressor cannot be energized which prevents the system from refilling the air struts and ride height drops over time.
- Check engine light: Not always
- Emissions related: No
- Repair difficulty: medium
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
Common causes
Ordered by how often each turns out to be the cause.
- Compressor relay failedCommon
- Relay wiring or fuse faultPossible
- Internal module faultLess likely
Parts involved
- Compressor Relay
- Air Compressor
- Air Suspension Module
C0301 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.