Powertrain, generic · Hybrid propulsion

P0C46 Hybrid/EV Battery Pack Coolant Temperature Sensor A Circuit Intermittent/Erratic

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P0C46 points to a battery coolant temperature signal that jumps faster than liquid in the loop can physically change temperature. GM's 2019 hybrid tables explain the check: every 100 ms the hybrid controller takes the difference to the previous inlet coolant value, adds up ten of these absolute steps and counts a failure when the sum exceeds 64 °C. Four seconds of failures within a five second window set the code, rated Type B with the MIL on the second trip. The test is suppressed while the hard circuit faults P0C44 or P0C45 are active, so P0C46 usually means a signal that is present but noisy. Loose terminals, contact corrosion or a harness that moves with the battery are the usual causes; wiggling the wiring with live data running helps locate it. Sensor B uses P0CD9.

Likely causes

Loose or spread terminal at the coolant sensor connector
Corrosion at connector or ground point
Harness rubbing or cracked near the battery coolant lines

Symptoms

  • MIL that may go out again for a while
  • Jumping coolant temperature in live data

Repair estimate

DifficultyHardWorkshop job
Parts and labour€60–400
Time0.5–3 h

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

Parts involved

hv battery pack coolant temp sensor awiring harnessbms

Related codes

P0C42P0C43P0C44P0C45P0CD9

References: gsi.ext.gm.com, law.cornell.edu.