Powertrain, generic · Hybrid propulsion

P0AB5 Hybrid/EV Battery Pack Air Temperature Sensor B Circuit Intermittent/Erratic

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P0AB5 is set when the signal of battery air temperature sensor B fluctuates in a way real air temperature cannot, typically from an intermittent contact. No manufacturer documents this exact code publicly; GM's two-mode tables, which use sensor B as the outlet air sensor, list only P0AB2 to P0AB4. As an analogy, GM's 2019 table judges the battery cell sensor code P0A9F by summing signal changes within 10-sample windows, failing after 4 of 5 bad windows, Type B. CARB requires hybrid temperature inputs to be checked for erratic behaviour. The fault often comes and goes with vibration or temperature. Move the outlet-side harness while watching live data to locate the weak point.

Likely causes

Loose or corroded terminal at sensor B
Partly broken wire near the outlet duct
Interference coupled into the sensor line

Symptoms

  • Hybrid warning light that appears intermittently
  • Outlet air value jumps in live data
  • No noticeable driving change in most cases

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–500
Time0.5–3 h

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

Parts involved

hv battery pack air temp sensor bwiring harnessbms

Related codes

P0AB1P0AB2P0AB3P0AB4P0AB0

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