P06B1
Sensor Reference Voltage B Circuit/OpenP06B1 is a generic OBD-II powertrain diagnostic trouble code: Sensor Reference Voltage B Circuit/Open. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P06B1 means
P06B1 is stored when the powertrain control module (PCM) detects an open circuit or an out-of-range condition on the sensor reference voltage circuit designated "B". The module supplies a regulated reference voltage, most commonly five volts, to a group of sensors so they can report values such as pressure, temperature, position, and speed. Reference circuits are labelled A, B, and C to aid fault isolation, and circuit B feeds a manufacturer-defined subset of sensors.
When the reference on circuit B is lost or incorrect, every sensor sharing that supply reads implausibly at the same time. The module then sees several out-of-range signals together, so P06B1 is often accompanied by a cascade of companion codes for sensors such as MAP, throttle position, or others on the same rail. Because the reference fault is the root cause, it must be resolved before chasing the downstream sensor codes.
The most frequent cause is a short to ground somewhere on the reference wire, which pulls the rail down, though an open conductor, a failed sensor, corroded connectors, or an internal module regulator fault can all be responsible. Diagnosis relies on the wiring diagram to identify the circuit B sensors, then measuring the reference voltage and unplugging sensors one at a time to isolate the fault before any part is replaced.
Common causes
Most-frequently reported root causes when P06B1 is logged.
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1
Short to ground on the reference voltage "B" circuit wiring.
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2
Open circuit in the reference "B" wire from a broken or corroded conductor.
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3
A sensor on circuit B with an internal short pulling the reference low.
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4
Chafed or pinched harness wiring contacting ground on the reference wire.
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5
Corroded or loose connector creating a partial short or open in the reference supply.
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6
Short to another circuit or to voltage on the reference "B" wire.
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7
Failed internal reference voltage regulator inside the PCM for circuit B.
Symptoms drivers notice
How to diagnose P06B1
A typical diagnostic flow when this code is present.
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1
Record all DTCs; multiple sensor range or circuit codes alongside P06B1 point to a shared reference fault.
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2
Use the wiring diagram to identify which sensors are supplied by the circuit B reference.
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3
Measure the circuit B reference voltage at the module and at the sensor connectors.
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4
Unplug sensors on circuit B one at a time and watch for the reference to recover, isolating a shorted sensor.
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5
Inspect the reference wire along its length for chafing, pinches, opens, or connector corrosion.
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6
If the reference is normal with all sensors disconnected but the harness is intact, suspect the PCM regulator.
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7
Repair the short or open, reconnect sensors, clear codes, and verify all sensor readings are within range.
Vehicles where we've handled P06B1
Platforms in our catalogue with confirmed P06B1 coverage.
Related powertrain codes
- P0600 — Serial Communication Link Malfunction
- P0601 — Internal Control Module Memory Check Sum Error
- P0602 — Control Module Programming Error
- P0603 — Internal Control Module Keep Alive Memory (KAM) Error
- P0604 — Internal Control Module Random Access Memory (RAM) Error
- P0605 — Internal Control Module Read Only Memory (ROM) Error
Frequently asked questions
Why do multiple sensor codes appear with P06B1?
Sensors sharing the same reference circuit all read incorrectly when that reference is lost or pulled out of range, so P06B1 is usually the root cause code to fix first.
How do I find which sensor is shorting the reference?
Unplug the circuit B sensors one at a time while monitoring the reference voltage; when the voltage recovers after unplugging one sensor, that sensor is the source of the short.
Can P06B1 cause a no-start condition?
Yes. If an important sensor such as MAP or crank position shares circuit B and loses its reference, the engine may not start or may stall while running.
Are the same sensors always on circuit B?
No. The grouping of sensors on reference circuits A, B, and C is manufacturer specific, so the correct wiring diagram is needed to identify the circuit B sensors for the vehicle.
Disabling P06B1 in software
RaceTune can permanently disable P06B1 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
ECU families we can disable P06B1 on
We hold the DaVinci A2L disable definitions for these families, so the exact P06B1 path and mask addresses are mapped. verified marks a confirmed disable definition. We support many more — upload your file and our identifier will match it automatically.
- Bosch EDC17C74 verified
- Bosch MD1CP004 verified
- Bosch MG1CP002 verified
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
Got P06B1 in your scan?
Upload your ECU file — we'll identify the exact software version and confirm whether a disable is available for your car.
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