Faulty transmission mode switch B or mode selector button (internal open circuit or stuck contacts); Open circuit or high resistance in the switch signal wiring, giving a high voltage reading; Corroded, loose or damaged connector terminals at the switch or transmission control module; Signal wire shorted to a voltage supply; Liquid ingress or wear in the gear selector or console switch assembly; Faulty transmission control module or a software issue where a calibration fault is a known cause for the model.

P071F

Transmission Mode Switch B Circuit High.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
7: AreaTransmission
1F: FaultThe specific fault in that area

What it means

P071F is a generic code meaning the transmission control module has detected a high voltage in the Transmission Mode Switch B circuit. The module saw a signal voltage above the expected range, which usually points to an open circuit, a short to voltage or a faulty switch. The exact switch location and function (for example sport, snow, tow or economy mode) depend on the make and model.

Symptoms

Gearbox warning light or malfunction indicator lamp on
Selected drive mode (sport, snow, tow or economy) does not engage or cannot be changed
Gearbox stuck in a default mode or limp-home strategy
Harsh, delayed or unusual gear changes
Drive mode indicator on the dash not matching the selected mode
Poor fuel economy if the gearbox stays in a fixed mode

Possible causes

Faulty transmission mode switch B or mode selector button (internal open circuit or stuck contacts)likely
Open circuit or high resistance in the switch signal wiring, giving a high voltage readinglikely
Corroded, loose or damaged connector terminals at the switch or transmission control modulelikely
Signal wire shorted to a voltage supplypossible
Liquid ingress or wear in the gear selector or console switch assemblypossible
Faulty transmission control module or a software issue where a calibration fault is a known cause for the modelrare

How to diagnose

Read all stored and pending codes and the freeze frame data, noting whether other transmission or network codes are present
Check for manufacturer bulletins or known issues for the specific model and gearbox
Operate the mode switch and watch live data to see if the switch state or voltage changes as expected
Visually inspect the switch, console area and wiring for damage, spilled liquid, chafing or corrosion
Disconnect and inspect the connectors at the switch and control module for bent, pushed-back or corroded terminals
Check the switch reference supply, signal and ground circuits with a multimeter against the wiring diagram, looking for opens and shorts to voltage
Test the switch itself for correct resistance or continuity in each position
Only if wiring and switch are proven good, consider control module faults and check for any applicable software update

How to fix

Replace the faulty mode switch or selector assembly
Repair or replace damaged wiring that is open or shorted to voltage
Clean or replace corroded connectors and repair loose terminals
Dry out and clean the console area, then replace any switch damaged by liquid
Update or reprogram the control module software if an outdated calibration is a known cause, or replace the module if confirmed faulty
Clear the code and road test to confirm it does not return

Can I keep driving?

Medium severity

The car can usually be driven carefully as the gearbox typically defaults to a standard mode, but get it checked soon. If it enters limp mode or shifts harshly, limit driving to avoid further gearbox stress.

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