P0A02
Motor Electronics Coolant Temperature Sensor Low Input
Voltage at motor electronics coolant temperature sensor below threshold. The engine coolant temperature sensor feeds warm-up enrichment, fan control and closed-loop entry — a stuck-cold reading keeps the engine in open loop and rich forever.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: shop_only
Common causes
Ordered by how often each turns out to be the cause.
- Short to groundCommon
Parts involved
- Motor Electronics Coolant Temperature Sensor
- Wiring Harness
P0A02 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.