P2185: Engine Coolant Temperature Sensor 2 Circuit High
What to do
Expect noticeably worse fuel economy and possibly a fuel smell — the engine is being fuelled as if it were freezing cold. Worth fixing promptly on cost alone, and because sustained over-fuelling is hard on the catalytic converter. If any work has recently been done in that area of the engine, ask for the connector to be checked first; a sensor knocked loose gives exactly this code.
What this code means
The second coolant sensor circuit reads above its valid voltage range — an open circuit, a disconnected sensor, or a sensor failed to a very high resistance.
By the thermistor logic set out at P2184, a high circuit voltage means a low indicated temperature. The module is being told the engine is extremely cold, and it acts accordingly.
That has a consistent and costly signature: the engine is fuelled as though permanently starting from cold. Enrichment stays on, the mixture runs rich indefinitely, fuel economy falls sharply, and the excess fuel reaches a catalytic converter that is being asked to deal with far more than it was designed for. Every consequence listed under P2181 for an engine running cold applies here even though the engine itself may be at perfectly normal temperature — because the fault is in what the module believes, not in the coolant.
An open circuit is also what a disconnected connector looks like, which makes this a code worth checking physically before testing anything. Coolant sensors sit in awkward places and get knocked off during unrelated work, and the connector locking tabs become brittle with heat and age.
Likely causes
Start here
- Open circuit in sensor wiring · moderate
- Disconnected sensor connector · easy
- Faulty engine coolant temperature sensor · easy
- Corroded or loose connector · easy
Less common
- Poor sensor ground connection · moderate
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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