P2DA4
Coolant Heater A Internal Control Module Performance
The internal control module of coolant heater A reports a performance fault. Internal self-tests fail.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Symptoms
- Check engine light on
- Possible limp mode or no-start
- Multiple follow-up faults across modules
- Reset/relearn may be needed after repair
Common causes
Ordered by how often each turns out to be the cause.
- Internal module faultCommon
- Firmware corruptionPossible
- Module software outdated, reflash may resolveLess likely
Parts involved
- Coolant Heater A
- Coolant Heater A Control Module
P2DA4 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.