Powertrain, generic · Hybrid propulsion

P0ACA Hybrid/EV Battery Temperature Sensor C Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

Battery temperature sensor C is a further thermistor inside the high-voltage pack, corresponding to sensor 3 in GM's Volt bulletin. P0ACA covers a general electrical fault in its circuit that the controller does not narrow down to low, high or erratic. No manufacturer documents this exact code publicly; GM reports the more specific siblings P0ACB to P0ACE instead. CARB requires temperature sensors of hybrid batteries to be monitored like other input components. Losing one temperature input makes the controller more cautious: expect reduced charge and assist power and a hybrid warning. Since sensors C and B often share the same sensing board, check whether neighbouring sensor codes are stored as well.

Likely causes

Poor contact or damaged wire between sensor C and sensing board
Temperature sensor C failed
Fault in the battery controller input stage

Symptoms

  • Hybrid system or check engine warning
  • Reduced electric power and regeneration
  • Further battery sensor codes may be stored

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€150–2,500
Time1–5 h

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

Parts involved

hv battery temp sensor cwiring harnessbms

Related codes

P0ACBP0ACCP0ACDP0ACEP0AC5P0AE8

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