Faulty Park position sensor/switch or transmission range sensor, or its internal circuit; Wiring chafed or shorted to ground between the sensor and the transmission control module; Damaged, corroded or water-affected connector at the sensor or control module; Selector linkage or cable out of adjustment so the switch reads the wrong position; Low or unstable supply or reference voltage to the sensor; Faulty transmission control module.

P07B3

Transmission Park Position Sensor/Switch A Circuit Low.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
7: AreaTransmission
B3: FaultThe specific fault in that area

What it means

P07B3 is a generic code meaning the transmission control module has seen a low voltage or signal in the circuit for Park position sensor or switch A. The module compares the signal with the selector position and other range sensor inputs, and sets the code when the Park signal sits below the expected range, such as when it is shorted to ground or open in a way that pulls the signal low.

Symptoms

Engine will not start, or cranks only in certain selector positions
Gear selector position shown incorrectly on the dashboard
Transmission warning light or general warning message
Reverse lights or start inhibit behaving erratically
Harsh, delayed or missing gear engagement
Transmission may default to a limited operating mode

Possible causes

Faulty Park position sensor/switch or transmission range sensor, or its internal circuitlikely
Wiring chafed or shorted to ground between the sensor and the transmission control modulelikely
Damaged, corroded or water-affected connector at the sensor or control modulelikely
Selector linkage or cable out of adjustment so the switch reads the wrong positionpossible
Low or unstable supply or reference voltage to the sensorpossible
Faulty transmission control modulerare

How to diagnose

Read all stored codes and freeze frame data, noting any other range sensor, supply voltage or communication codes, then check for related technical bulletins for the model
Check the battery condition and charging voltage, as low voltage can upset transmission signals
Inspect the sensor wiring and connectors for chafing, oil contamination, corrosion, water ingress and bent or pushed-back pins
Check the selector position shown on a scan tool live data against the actual lever position in each gear
Check the selector cable or linkage adjustment and look for wear or damage, following the manufacturer procedure for the model
Measure the sensor supply, ground and signal circuits against the wiring diagram, and test for a short to ground with the connector unplugged
Test the sensor or switch against the manufacturer specification, as the type and test values vary by model and transmission
If wiring and sensor are good, check the control module power and grounds before considering the module

How to fix

Replace the Park position sensor/switch or range sensor if it fails testing, and adjust it as the manufacturer specifies
Repair or replace damaged wiring that is shorted to ground
Clean, repair or replace faulty connectors and terminals
Adjust or repair the selector cable or linkage
Repair supply or ground faults found on the sensor circuit
Repair or replace the transmission control module, with any required programming, only after other causes are ruled out

Can I keep driving?

Medium severity

The car may be driveable, but it can fail to start or may enter a limited transmission mode without warning. Get it checked soon and avoid long journeys until the fault is fixed.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.