What it means
Same as P05D0 with the signal shorted to ground. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
How it works
Switch A sends the driver's mode selection to the vehicle controller through a signal circuit. P05D1 sets when that signal is abnormally low, consistent with a short to ground or another fault pulling the switch A input down.
Common causes
Most likely first.
- Signal shorted to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Drive-mode selection may be unavailable or unchanged
- A drive-mode warning or check-engine light may illuminate
How to diagnose it
- Use a scan tool to observe switch A's reported state while operating the control and note whether the input stays low.
- Inspect switch A's connector and harness for chafing, moisture, corrosion, or pushed-back pins that could ground the signal.
- With the wiring diagram, check the switch A signal for a short to ground, isolating sections of the harness as directed by service information.
- Wiggle the switch A harness while monitoring the input to reveal an intermittent ground fault.
- If the harness is clear, test switch A and its ground and signal connections against the manufacturer's specification.
Common fixes
- Dry, clean, and secure the switch A connector or restore a pushed-back terminal.
- Repair chafed switch A signal wiring that is contacting ground.
- Replace switch A if it continues to pull the signal low when disconnected and tested as specified.
- Repair a confirmed fault in the controller input circuit.
Can I keep driving?
The vehicle is generally driveable if it runs and responds normally, but switch A may not change the drive mode. Do not depend on selecting a special mode for low-traction conditions.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.