What Does P06B2 Mean?
The sensor power supply circuit "A" is reporting a voltage higher than the expected maximum threshold (typically above 5.25V when it should be a stable 5.0V). An overvoltage on the reference circuit can cause all connected sensors to read higher than actual values. The driver may notice check engine light, rough running, incorrect gauge readings, and potential transmission shift issues.
Common Causes
35%
PCM internal 5V regulator malfunction outputting excessive voltage on the A circuit
30%
Short between the 5V reference wire and a higher voltage source (12V) in the wiring harness
20%
Corroded ground connection for the sensor return circuit causing a floating reference voltage
10%
Aftermarket wiring modification that inadvertently feeds voltage into the reference circuit
5%
Charging system overvoltage condition elevating all PCM internal references
Diagnostic Steps
1
Measure the 5V reference A voltage at the PCM connector — it should read between 4.95V and 5.05V; document the actual reading.
2
If voltage is above 5.25V, disconnect all sensors from the A circuit and recheck the PCM output voltage to determine if the fault is internal to the PCM or caused by external wiring.
3
Inspect the wiring harness for any location where the 5V reference wire runs adjacent to 12V power wires — look for melted insulation, chafing, or improper splices.
4
Verify the charging system output is within specification (13.5V-14.7V) to rule out overvoltage as a contributing factor.
5
Check sensor ground/return circuit continuity and resistance — a floating ground can cause the reference to read high.
Estimated Repair Cost
$75 - $1,200
Parts + labor, varies by vehicle and location
The sensor power supply circuit "A" is reporting a voltage higher than the expected maximum threshold (typically above 5.25V when it should be a stable 5.0V). An overvoltage on the reference circuit can cause all connected sensors to read higher than actual values. The driver may notice check engine...
The most common cause of P06B2 (Sensor Power Supply "A" Circuit High) is: PCM internal 5V regulator malfunction outputting excessive voltage on the A circuit
Typical repair costs for P06B2 range from $75 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
High reference voltage causes sensors to over-report values, which can result in lean fuel conditions, overheating, and transmission shift problems. The vehicle should be diagnosed promptly to prevent catalytic converter damage from lean operation.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P06B2 to identify the root cause.
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Quick Info
Category
Powertrain
System
Sensor Reference Voltage / Engine Control
Difficulty
Type
Generic (SAE)
Recommended Tools
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