Powertrain, generic (extended)

P2186 Engine Coolant Temperature Sensor 2 Circuit Intermittent/Erratic

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

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.

Likely causes

Worn or loose pins in the sensor 2 connector
Wire broken inside its insulation or chafed harness making intermittent contact
Sensor 2 with an intermittent internal fault

Symptoms

  • Check engine light after two drives
  • Fans switching on and off irregularly
  • Temperature-related messages that appear and vanish

Repair estimate

DifficultyEasyDIY possible
Parts and labour€30–250
Time0.5–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

engine coolant temperature sensor 2sensor wiring

Related codes

P2184P2185P2182P2183P0119P01E7

References: gsi.ext.gm.com, static.nhtsa.gov, law.cornell.edu.