P2C37 code meaning
Cold Start Engine Coolant Pump Performance
Powertrain system Generic code P2Cxx codes Check engine light
What P2C37 means
Engines with a switchable or electric main coolant pump often keep the coolant still, or nearly so, right after a cold start so the cylinder head and catalyst warm up sooner. P2C37 reports that the pump did not behave as commanded during this cold-start phase, for example running when it should rest or failing to start when flow is requested. California rules require separate codes for faults detected during a cold-start strategy and ask makers of electric water pumps to submit a monitoring plan of their own. No manufacturer documents P2C37 publicly. An Audi patent shows one way to judge such a pump: once it is switched back on, the measured head temperature is checked against a model value derived from coolant temperature. Related are P2DE9/P2E82 (cold-start under- and overspeed) and P26CB.
P2C37 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyHard
- Typical labor1 to 4 hours
- Clears after repairAfter a drive cycle
Symptoms of P2C37
- MIL on
- Slow warm-up and weak cabin heat, or rising temperature when the pump stays off
- Overheating warning possible in severe cases
Common causes of P2C37
- Most likelySwitchable pump stuck engaged or disengaged (clutch, shroud or valve actuator)
- PossibleElectric coolant pump with failing motor or electronics
- PossibleAir in the system or low coolant level
- Less likelyCoolant or head temperature sensor reading wrong and misleading the check
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Engine coolant pumpEngine coolant loop
What each part of P2C37 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| C | Area: hybrid propulsion. |
| 37 | The exact fault in that area. |
What to do next
- Note P2C37 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2C37
What does P2C37 mean?
P2C37 means "Cold Start Engine Coolant Pump Performance". Engines with a switchable or electric main coolant pump often keep the coolant still, or nearly so, right after a cold start so the cylinder head and catalyst warm up sooner. It is a generic code, so it means the same on every make.
Is it safe to drive with P2C37?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P2C37 fail an emissions test?
Yes, it can. P2C37 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2C37 to fix?
Difficulty: hard. A typical repair takes 1 to 4 hours of work. This is a job for a workshop.
Will P2C37 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.