Low battery voltage or poor power and earth supply to the control module; Corroded, loose or damaged connector pins or wiring at the control module; Internal temperature sensor fault inside the control module; Module overheating due to heat soak, poor mounting or water ingress; Outdated or faulty control module software where the manufacturer has a known fix; Failed control module internal electronics.

P06AC

Control Module Internal Temperature Sensor B Range/Performance.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
6: AreaComputer and output circuits
AC: FaultThe specific fault in that area

What it means

P06AC is a generic code meaning the powertrain control module has found the signal from its internal temperature sensor B to be implausible or out of the expected range. The module compares this reading with other temperature data, such as engine coolant and intake air temperature after a long cold soak, or with the expected rate of change, and the values do not agree. This points to a fault in the module itself or in its supply, rather than a problem with the engine.

Symptoms

Engine management warning light on
Stored fault with no obvious driveability change
Reduced performance or limp mode in some cases
Hard starting or intermittent stalling if the module is struggling
Other module or communication codes stored alongside it

Possible causes

Low battery voltage or poor power and earth supply to the control modulelikely
Corroded, loose or damaged connector pins or wiring at the control modulepossible
Internal temperature sensor fault inside the control modulepossible
Module overheating due to heat soak, poor mounting or water ingresspossible
Outdated or faulty control module software where the manufacturer has a known fixrare
Failed control module internal electronicsrare

How to diagnose

Read all stored codes and freeze frame data, noting engine temperature, battery voltage and whether the engine was cold or hot when the code set
Check for related codes covering module supply voltage, processor or communication faults, and deal with those first
Test battery condition and charging system output, as low or unstable voltage can upset module readings
Inspect the control module, its connectors and wiring for corrosion, water ingress, heat damage or loose pins
Check the module power feeds and earths for voltage drop under load
Check the module mounting position for excessive heat from nearby components or poor airflow
Compare live module temperature data, if available, with coolant and intake air temperatures after the car has been cold soaked
Check whether the manufacturer has published a software update or technical bulletin for this code on the specific model and engine

How to fix

Charge or replace a weak battery and repair any charging system fault
Repair or replace damaged wiring, terminals and connectors, and fix any poor earth connection
Dry out and seal any water ingress source, then replace the module if it has been damaged by moisture
Restore proper cooling or heat shielding around the module where it is overheating
Update the control module software where an outdated calibration is a known cause
Replace and program the control module only after supply, wiring and software have been ruled out

Can I keep driving?

Medium severity

The car can usually be driven for a short time while you arrange a repair, but get it checked soon as a failing module could cause stalling or limp mode. Avoid long journeys if the car is running poorly or other warning lights appear.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.