C0099
ABS Control Module Internal Fault
The ABS control module fails its internal self-test (RAM, ROM or processor watchdog). ABS and stability control are disabled.
- Check engine light: Not always
- Emissions related: No
- Repair difficulty: hard
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.
- Module internally failedCommon
- Power supply undervoltage during operationPossible
Parts involved
- ABS Control Module
C0099 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.