P07BD
Transmission Park Position Sensor/Switch B Circuit Intermittent/Erratic.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 7
- AreaTransmission
- BD
- FaultThe specific fault in that area
What it means
P07BD means the transmission control unit has seen the signal from the second (B) Park position sensor or switch circuit drop out, jump or give readings that don't match the selector position. The signal is intermittent or erratic rather than stuck. Which circuit is 'B', and whether it is part of a combined range sensor, varies by vehicle and transmission type.
Symptoms
- Engine intermittently refuses to start, or starts in Neutral but not Park, or the reverse
- Gear selector display flickers or shows the wrong position
- Warning light on, or transmission warning message displayed
- Reversing lights or shift-lock release working intermittently
- Harsh, delayed or inconsistent engagement, or transmission held in a limited mode
- Fault comes and goes, often with vibration, heat or damp
Possible causes
- Damaged, chafed or corroded wiring or loose connector pins in the Park position sensor B circuitlikely
- Faulty or worn Park position switch or transmission range sensorlikely
- Selector cable or linkage out of adjustment, or the sensor not aligned with the selector shaftpossible
- Water or fluid contamination in the sensor or connectorpossible
- Poor power or earth supply to the sensor, or low system voltagepossible
- Worn selector lever or gear shift assembly giving unreliable contactrare
- Internal fault in the transmission control unitrare
How to diagnose
- Read all stored codes and freeze frame data, noting selector position, vehicle speed and battery voltage when the fault set, and check for related range sensor or start-inhibit codes
- Check battery condition and charging voltage, as low voltage can cause erratic sensor signals
- Visually inspect the sensor, its connector and the harness for chafing, fluid, corrosion, bent or pushed-back pins and water ingress
- With the system live, watch the Park/Neutral/range signal on a scan tool while moving the selector through each position and gently wiggling the harness to provoke a dropout
- Check the selector cable or linkage adjustment and that the sensor position matches the selector, following the manufacturer's procedure for the model
- Test the supply, earth and signal wiring for voltage, continuity and shorts using the wiring diagram
- Check the sensor's resistance or switch state in each position against specification, where the manufacturer gives one
- Check for software updates or technical bulletins for the vehicle before suspecting the control unit
How to fix
- Repair or replace damaged wiring and clean or renew corroded or loose connector terminals
- Replace the faulty Park position switch or range sensor and set it up as the manufacturer specifies
- Adjust or renew the selector cable or linkage and re-align the sensor
- Cure any water or fluid leak into the connector and renew contaminated parts
- Correct supply or earth faults, and fix battery or charging problems
- Replace the transmission control unit, or apply an official software update if one is a known remedy, only after the wiring and sensor are proven good
Can I keep driving?
The car can usually be driven short-term, but it may fail to start or restart without warning, or run in a limited transmission mode. Get it checked soon, and always use the handbrake when parking as the Park signal may not be reliable.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.