What it means
Same as P05D2 on switch B. 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 B reports the driver's mode selection to the vehicle controller on a separate electrical signal circuit. P05D6 sets when that signal is abnormally high, consistent with a short to supply or another fault holding the switch B input high.
Common causes
Most likely first.
- Signal shorted to supply
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
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 monitor switch B's input while operating it and note whether the reported state stays high.
- Inspect switch B's connector and wiring for pinched insulation, corrosion, moisture, or contact with a supply circuit.
- With the wiring diagram, check the switch B signal for a short to supply and isolate harness sections using service information.
- Wiggle the switch B harness while monitoring live data to reveal an intermittent short.
- If the wiring checks out, test switch B and the controller input against the manufacturer's specification.
Common fixes
- Secure or clean the switch B connector and correct any terminal contact issue.
- Repair pinched switch B signal wiring that is touching a supply wire.
- Replace switch B if testing confirms it produces an abnormally high signal.
- Repair a confirmed fault in the controller input circuit.
Can I keep driving?
You can generally drive if the vehicle behaves normally, but switch B may not select the mode you request. Avoid relying on a particular drive mode until the fault is repaired.
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.