P0598
PowertrainEngine Coolingmoderate severityThermostat Heater Control Circuit Low
What P0598 Means
The thermostat heater control circuit voltage is too low. A short to ground or failed heater element is the likely cause.
Symptoms
- Check engine light illuminated
- Poor engine temperature control
- Reduced fuel economy
Common Causes
- Short to ground in heater circuit
- Faulty heated thermostat
- Damaged wiring harness
- PCM output fault
Diagnostic Steps
- Read thermostat heater codes
- Check circuit for short to ground
- Inspect harness near thermostat
- Measure control voltage during operation
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