P07BA

What it means

P07BA is a generic code meaning the control unit has detected a high voltage or signal level in the 'B' circuit of the transmission park position sensor or switch. The transmission or powertrain control unit monitors this input to know whether the transmission is in Park, and it sets the code when the signal sits above the expected range, typically from a short to voltage, an open circuit that pulls the line high, or a faulty sensor. Exact circuit layout and which unit monitors it vary by vehicle.

Symptoms

• Warning light on, such as the engine or transmission fault lamp
• Engine will not crank or start in Park, or only starts in Neutral
• Shift lever position display wrong or flashing
• Gear selector feels normal but the car will not shift out of Park or will not engage drive
• Reversing lights or shift interlock not working correctly
• Transmission may default to a limp mode on some models

Possible causes

• Faulty park position sensor or switch (internal fault giving a high signal)likely
• Damaged, chafed or corroded wiring, or a short to voltage on the B circuitlikely
• Poor connection, water ingress or corrosion at the sensor or transmission connectorlikely
• Open circuit or high resistance in the signal or ground wire pulling the signal highpossible
• Misadjusted or worn selector linkage or cable so the switch reads an invalid positionpossible
• Faulty transmission or powertrain control unit, or an outdated calibration where the manufacturer has issued an updaterare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting any other transmission, start or shift-position codes
2. Check the live data for the park position sensor or switch state while moving the selector through each position, and compare with the expected values for the model
3. Inspect the sensor, connector and wiring harness for chafing, heat damage, corrosion, water and bent or pushed-back pins
4. Check the selector linkage or cable adjustment and the physical condition of the selector mechanism
5. Check the sensor supply, signal and ground circuits with a multimeter against the manufacturer's wiring diagram, looking for a short to voltage, open circuit or high resistance
6. Test the sensor or switch itself against the manufacturer's specification, as the procedure depends on the model and transmission
7. Check for technical service bulletins or a calibration update for the transmission control unit before condemning it

How to fix

• Repair or replace damaged wiring and fix any short to voltage or open circuit
• Clean or repair corroded or loose connectors and seal out any water ingress
• Replace the park position sensor or switch if it fails testing
• Adjust or repair the selector linkage or cable
• Update the control unit calibration if an update is known to address this fault, or replace the unit only once all other causes are eliminated
• Clear the code after repair and road test to confirm it does not return

Can I keep driving?

Nearby codes

• P07B9GenericTransmission Park Position Sensor/Switch B Circuit Low
• P07BBGenericTransmission Park Position Sensor/Switch B Circuit Performance/Low