Faulty driver mode select switch B (internal short or worn contacts); Damaged wiring shorted to earth in the switch signal circuit; Corroded, loose or water-damaged connector at the switch or control unit; Open circuit or high resistance in the reference supply to the switch causing a low signal; Liquid ingress or debris in the switch assembly, for example from a spilled drink; Fault within the control unit input circuit or an outdated calibration, where the manufacturer has identified one.

P05D5

Driver Mode Select Switch B Circuit Low.

Generic
Powertrain
Generic code
Low severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
5: AreaVehicle speed, idle control and auxiliary inputs
D5: FaultThe specific fault in that area

What it means

P05D5 is a generic powertrain code meaning the control unit has detected a low voltage signal in the circuit for driver mode select switch B. The module monitors the switch input and sets the code when the voltage sits below the expected range, which points to a short to earth, an open circuit with a pulled-down signal, or a faulty switch. How the switch is used (drive mode, throttle response, transmission or traction settings) depends on the make and model.

Symptoms

Drive mode selector does not respond or does not change modes
Car stuck in a default driving mode
Warning light or mode-related message on the dashboard
Altered throttle response or gearshift behaviour
Engine management light on

Possible causes

Faulty driver mode select switch B (internal short or worn contacts)likely
Damaged wiring shorted to earth in the switch signal circuitlikely
Corroded, loose or water-damaged connector at the switch or control unitpossible
Open circuit or high resistance in the reference supply to the switch causing a low signalpossible
Liquid ingress or debris in the switch assembly, for example from a spilled drinkpossible
Fault within the control unit input circuit or an outdated calibration, where the manufacturer has identified onerare

How to diagnose

Read all stored and pending codes and note the freeze frame data, checking for other switch, supply voltage or communication codes
Check the selector operation and whether the mode display responds, and note any spill damage or physical wear around the switch
Inspect the switch connector and wiring for corrosion, bent pins, chafing and moisture, and repair any obvious damage
Using live data, watch the switch B status or voltage while operating the selector and compare against the manufacturer specification
With the switch unplugged, measure the reference supply and signal voltage at the harness side using the wiring diagram for that model
Check the signal wire for a short to earth and for continuity back to the control unit, with the battery disconnected as the procedure requires
Test the switch resistance or output in each position against specification, as the design varies by model
Check for any technical service information or calibration updates for the vehicle before condemning the control unit

How to fix

Replace the driver mode select switch B if it fails testing
Repair or replace the damaged wiring where it is shorted to earth
Clean or replace corroded or damaged connectors and pins, and ensure they are properly seated and sealed
Restore the reference supply by repairing the open circuit or high resistance fault
Replace or repair the control unit only after wiring and switch are proven good, and apply any manufacturer-approved calibration update if one is a known fix
Clear the code and road test to confirm it does not return

Can I keep driving?

Low severity

The car can normally be driven as it will usually default to a standard mode, but get it checked soon. If the car drives abnormally or other warnings appear, have it inspected sooner.

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