P07B4

What it means

P07B4 means the transmission control module has seen a voltage that is too high on the circuit for park position sensor or switch A. The signal sits above the expected range, which usually points to a short to voltage, an open circuit that lets the signal float high, or a faulty sensor or switch. The exact sensor type, location and signal range depend on the vehicle and transmission.

Symptoms

• Engine will not crank or starts only in certain selector positions
• Gear selector position shown incorrectly on the dashboard
• Transmission warning light or malfunction indicator lamp on
• Vehicle will not shift out of Park or the shift lock behaves oddly
• Reverse lights or park/neutral start function not working correctly
• Transmission goes into a limited operating mode

Possible causes

• Faulty park position sensor or switch, or a range selector assembly with an internal faultlikely
• Damaged, corroded or loose connector at the sensor or transmission control modulelikely
• Signal wire short to voltage or open circuit in the signal or ground wirepossible
• Selector or sensor misaligned or poorly adjusted, giving an out-of-range readingpossible
• Fault in the transmission control module or its internal circuitrare
• Water or fluid ingress in the transmission harness or sensor connectorpossible

How to diagnose

1. Read all stored and pending codes and note the freeze frame data, including selector position and battery voltage
2. Check for related codes covering other range or position sensors, supply voltage or communication faults
3. Inspect the sensor, connectors and harness for damage, corrosion, fluid ingress or chafing
4. Check battery condition and charging voltage, as low or unstable voltage can cause circuit faults
5. With a scan tool, watch the park position signal while moving the selector through every position and note any wrong or stuck readings
6. Using the manufacturer's wiring diagram, test the sensor supply, signal and ground for short to voltage, open circuit and resistance
7. Check the selector and sensor alignment or adjustment against the manufacturer's procedure for that model
8. If wiring and the sensor test fine, check for software updates and have the control module tested

How to fix

• Repair or replace damaged wiring, and clean or replace corroded connectors
• Replace the park position sensor, switch or range selector assembly if it is faulty
• Adjust or realign the selector and sensor to specification where the model allows
• Dry out and seal the connector or harness if water or fluid has got in, and replace it if damaged
• Apply any manufacturer software update for the transmission control module if it addresses this fault
• Repair or replace the transmission control module only after the wiring and sensor have been proven good

Can I keep driving?

Nearby codes

• P07B3GenericTransmission Park Position Sensor/Switch A Circuit Low
• P07B5GenericTransmission Park Position Sensor/Switch A Circuit Performance/Low