What Does P06AC Mean?
The PCM/ECM/TCM internal temperature sensor "B" is reporting readings outside its expected range or is not responding consistently. This is a secondary internal temperature monitoring circuit within the powertrain control module itself. The driver may notice erratic engine behavior, transmission shifting issues, or the PCM entering a protective limp mode to prevent heat damage to internal circuitry.
Common Causes
40%
PCM/ECM internal component degradation or thermal damage causing erratic sensor readings
25%
Poor PCM ground connections creating electrical noise affecting internal sensor accuracy
20%
PCM power supply voltage irregularities causing sensor reading drift
10%
Software calibration error or corrupted firmware in the control module
5%
Excessive underhood temperatures from external heat sources affecting the PCM housing
Diagnostic Steps
1
Monitor PCM internal temperature PID values on both sensor A and sensor B — compare readings; they should track within 5°C of each other under identical conditions.
2
Check PCM power supply voltage at the module connector; verify battery voltage (12.4-14.7V) is stable with no AC ripple exceeding 50mV.
3
Inspect all PCM ground connections for corrosion, looseness, or damage — clean and re-torque to specification.
4
Verify the PCM housing is not exposed to excessive heat from nearby exhaust components; check for missing or damaged heat shields.
5
If all external circuits check out, perform a PCM reprogramming/reflash with the latest calibration from the manufacturer before considering PCM replacement.
Estimated Repair Cost
$150 - $1,500
Parts + labor, varies by vehicle and location
The PCM/ECM/TCM internal temperature sensor "B" is reporting readings outside its expected range or is not responding consistently. This is a secondary internal temperature monitoring circuit within the powertrain control module itself. The driver may notice erratic engine behavior, transmission shi...
The most common cause of P06AC (PCM/ECM/TCM Internal Temperature Sensor "B" Range/Performance) is: PCM/ECM internal component degradation or thermal damage causing erratic sensor readings
Typical repair costs for P06AC range from $150 to $1,500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The vehicle may enter limp mode unexpectedly, reducing power and drivability. While not immediately dangerous, the PCM could shut down to protect itself from perceived overheating, causing a stall. Drive cautiously to a repair facility and avoid prolonged driving in extreme heat.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P06AC to identify the root cause.
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Quick Info
Category
Powertrain
System
Engine Control Module
Difficulty
Type
Generic (SAE)
Recommended Tools
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