P0AB4 code meaning
Hybrid/EV Battery Pack Air Temperature Sensor B Circuit High
Powertrain system Generic code P0Axx codes Check engine light
What P0AB4 means
P0AB4 reports a signal from air temperature sensor B above the valid range. For an NTC thermistor that reads as extremely cold air, which points to an open circuit, a broken ground or a disconnected plug. GM uses the code for the outlet air sensor of its full-size two-mode hybrids; the 2011 and 2013 tables set it when the outlet reading falls below -45 °C in 30 of 40 samples, Type B, two trips. With the outlet value rejected, the controller also suspends the outlet plausibility test P0AB2 and runs the fan on a substitute strategy. Look for a connector left off after battery work or a broken wire at the duct. The shorted counterpart is P0AB3, the inlet-side equivalent P0AAF.
P0AB4 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 2.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P0AB4
- Check engine or hybrid warning light
- Outlet air shows about -40 °C in live data
- Battery fan on default operation
Common causes of P0AB4
- Most likelyOpen signal or ground wire of sensor B
- PossibleConnector not refitted after battery or duct work
- PossibleThermistor open internally
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hv battery pack air temp sensor bWiring harnessBms
What each part of P0AB4 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| A | Area: hybrid propulsion. |
| B4 | The exact fault in that area. |
What to do next
- Note P0AB4 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 P0AB4
What does P0AB4 mean?
P0AB4 means "Hybrid/EV Battery Pack Air Temperature Sensor B Circuit High". P0AB4 reports a signal from air temperature sensor B above the valid range. It is a generic code, so it means the same on every make.
Is it safe to drive with P0AB4?
Drive gently and only to a workshop. With P0AB4 the car can go into limp mode (reduced power) to protect itself.
Will P0AB4 fail an emissions test?
Yes, it can. P0AB4 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 P0AB4 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. This is a job for a workshop.
Will P0AB4 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.