P0538
A/C Evaporator Temperature Sensor Circuit High
The evaporator temperature sensor signal voltage is above the upper diagnostic threshold. Typically open circuit or short to power.
- Check engine light: Not always
- Emissions related: No
- Repair difficulty: easy
Common causes
Ordered by how often each turns out to be the cause.
- Sensor open internallyCommon
- Wiring open or disconnectedPossible
- Connector pins corroded - high contact resistanceLess likely
Parts involved
- AC Evaporator Temp Sensor
- Sensor Wiring
P0538 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.