P2B74 — Coolant Heater A Control Circuit High
The control circuit of coolant heater A reports a control circuit high condition. Auxiliary preheating of the coolant cannot be commanded as expected.
General code reference. Confirm the definition and diagnostic procedure for your vehicle's year, model and engine. A stored code alone does not identify a failed part.
Affected components
- Coolant heater a
- Wiring harness
- Ecm
Possible causes to check
These are possible checks, not a ranked diagnosis. Follow the vehicle manufacturer's test procedure before replacing parts.
- Control wire shorted to B+
- Open heater element
- Connector pins corroded - high contact resistance
Diagnostic notes
- The malfunction indicator lamp may illuminate
Related codes
Sources
Check each reference's vehicle and model-year scope. General background links do not establish which fault is most likely on your vehicle.
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.