P2182: Engine Coolant Temperature Sensor 2 Circuit
What to do
The car will normally drive, though the cooling fans may run more than usual as the module falls back on a safe default. Ask which sensor this is on your engine — if it is the one that measures radiator outlet temperature, this code also disables the cooling system check at P2181, so a genuine cooling fault could be hidden behind it. Worth repairing before concluding anything about the cooling system generally.
What this code means
A general fault in the circuit of the second engine coolant temperature sensor.
Why an engine has a second one is the useful part. A single sensor gives the module one temperature and no context. Two sensors placed at different points in the circuit give it a difference, and the difference is what makes the cooling system measurable rather than merely monitored. Placed at the engine outlet and the radiator outlet, the pair reports how much heat the radiator is actually removing; placed either side of the thermostat, it reports whether the thermostat has opened when it was supposed to.
That is how the performance code at P2181 is computed, and it is worth knowing that the two are linked: a fault in this sensor removes the module's ability to assess the cooling system at all, so this code frequently arrives with P2181 alongside it. Which came first matters — a genuine cooling problem and a failed sensor look similar in a code list and are entirely different repairs.
On some vehicles the second sensor exists for a simpler reason: one sensor drives the instrument gauge and the other drives the engine module, so that a failure of one does not take out both. Where that is the arrangement, a fault here can leave the engine running perfectly with the gauge behaving oddly, or the reverse.
Likely causes
Start here
- Faulty engine coolant temperature sensor · easy
- Corroded or loose connector · easy
- Damaged wiring harness · moderate
Less common
- Coolant leak into the sensor connector · easy
- Failed sensor reference voltage supply · 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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- The car — make, model, year and engine. The same fault behaves differently on each.
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