P2186 code meaning
Engine Coolant Temperature Sensor 2 Circuit Intermittent/Erratic
Powertrain system Generic code P21xx codes Check engine light
What P2186 means
P2186 covers a sensor 2 signal that jumps instead of changing smoothly. Coolant temperature moves slowly because of the mass of the liquid, so a step faster than physics allows points to a loose contact rather than a real change. GM's 2019 tables (19OBDG03D) work out an upper and lower limit for each new reading from the previous value and the sensor's time constant, about 7.4 s for sensor 2 within a -60 to 150 °C window; a reading outside this corridor for 5 s within 6 s sets the code as Type B, MIL after two trips. GM also lists P2186 among the effects of the chafed engine harness in bulletin 21-NA-149. Typical causes are worn connector pins, a wire broken inside the insulation or a sensor with an intermittent element. Steady low or high signals are P2184 and P2185.
P2186 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2186
- Check engine light after two drives
- Fans switching on and off irregularly
- Temperature-related messages that appear and vanish
Common causes of P2186
- Most likelyWorn or loose pins in the sensor 2 connector
- PossibleWire broken inside its insulation or chafed harness making intermittent contact
- Less likelySensor 2 with an intermittent internal fault
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Engine coolant temperature sensor 2Sensor wiring
What each part of P2186 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 1 | Area: fuel and air metering. |
| 86 | The exact fault in that area. |
What to do next
- Note P2186 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 P2186
What does P2186 mean?
P2186 means "Engine Coolant Temperature Sensor 2 Circuit Intermittent/Erratic". P2186 covers a sensor 2 signal that jumps instead of changing smoothly. It is a generic code, so it means the same on every make.
Is it safe to drive with P2186?
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 P2186 fail an emissions test?
Yes, it can. P2186 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 P2186 to fix?
Difficulty: easy. A typical repair takes 0.5 to 2.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P2186 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.