U0217: Lost Communication With Door Switch C
What to do
The car drives normally. See U0215 for the flat-battery consequence, which applies to any door switch.
If the fault is worse in winter and better in summer, say so — rear door latches sit in road salt and spray and are used far less often than front ones, so their contacts corrode undisturbed. That points at cleaning and freeing the latch rather than at anything electronic, and it is much the cheaper answer.
One thing worth knowing if you carry children: some cars use rear door opening to decide whether to remind you to check the back seats at the end of a journey. A rear door switch that reports nothing turns that reminder off without telling you. If you have been relying on it, do not.
What this code means
The third door switch has stopped being heard from. See U0215 for the family's framing and U0216 for identifying which door.
Switch C is normally a rear door, and rear door switches fail for a reason front ones largely do not: they are used rarely and left wet. A latch mechanism that is operated several times a day stays free; one that is used once a week sits in road film and salt spray, and its contacts corrode undisturbed.
That produces a characteristically seasonal fault — appearing in winter, easing in summer — which is worth reporting because it points at corrosion rather than at a component that has simply died.
A rear door switch also has one consequence the front ones do not, and it catches people out: child-seat and rear-passenger warnings. On vehicles with a rear occupant reminder, the system watches whether a rear door was opened before a journey to decide whether to remind the driver to check the back seats when they arrive. A rear door switch that reports nothing disables that reminder silently, and a driver who has come to rely on it should know it is not working.
Otherwise the causes are the family's: corrosion at the latch, the door harness boot, and water from a blocked drain.
Likely causes
Start here
Less common
- Broken wire in the door harness boot · moderate
- Damaged data bus wiring · moderate
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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