Cause
Water ingress into the module connector
Water reaching an electrical connector, and the single commonest cause of body-network faults on any vehicle — ahead of every electronic failure combined.
It behaves differently from a broken wire, and the difference is the diagnosis. Water conducts, so it does not simply interrupt a circuit; it bridges terminals, creating paths the designer never intended. A module may therefore behave erratically rather than stopping — reporting values that are electrically real and physically impossible — and it typically recovers as things dry out. A fault that follows the weather, appearing in rain and clearing in a dry spell, is this and effectively nothing else.
Then it stops being reversible. Water plus current plus dissimilar metals corrodes the terminal plating, so an intermittent fault becomes a permanent one, and by that point drying the connector no longer helps.
Where it comes from is the part worth pursuing, because replacing the component fixes nothing if the water still arrives. Blocked door drains, torn door vapour barriers, blocked sunroof and convertible drain channels, aged screen and light seals, plenum drains packed with leaf litter, and simple spillage into a footwell all deliver water to places that look dry from outside. Modules live inside doors, under seats and behind trim precisely where those paths end.
The tell is visible the moment somebody unlatches the plug — green or white deposits, dampness, or a terminal that has lost its shine. It is worth asking for explicitly, because a connector is normally checked for being connected rather than for being clean.
Typically a moderate job.
Some of these codes mean you should stop driving
1 of the 91 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (91)
Codes where this is a likely explanation first, rather than merely a possible one.
- U0118 Lost Communication With Fuel Additive Control Module Likely for this code Moderate
- U0133 Lost Communication With Active Roll Control Module Likely for this code Moderate
- U0134 Lost Communication With Power Steering Control Module — Rear Likely for this code High
- U0135 Lost Communication With Differential Control Module — Front Likely for this code Moderate
- U0136 Lost Communication With Differential Control Module — Rear Likely for this code Moderate
- U0137 Lost Communication With Trailer Brake Control Module Likely for this code High
- U0139 Lost Communication With Suspension Control Module B Likely for this code Moderate
- U0159 Lost Communication With Parking Assist Control Module A Likely for this code Moderate
- U0166 Lost Communication With Auxiliary Heater Control Module Likely for this code Moderate
- U0200 Lost Communication With Door Control Module B Likely for this code Low
- U0201 Lost Communication With Door Control Module C Likely for this code Low
- U0202 Lost Communication With Door Control Module D Likely for this code Low
- U0203 Lost Communication With Door Control Module E Likely for this code Low
- U0204 Lost Communication With Door Control Module F Likely for this code Low
- U0210 Lost Communication With Seat Control Module C Likely for this code Low
- U0213 Lost Communication With Mirror Control Module A Likely for this code Low
- U0215 Lost Communication With Door Switch A Likely for this code Low
- U0216 Lost Communication With Door Switch B Likely for this code Low
- U0217 Lost Communication With Door Switch C Likely for this code Low
- U0218 Lost Communication With Door Switch D Likely for this code Low
- U0219 Lost Communication With Door Switch E Likely for this code Low
- U0220 Lost Communication With Door Switch F Likely for this code Low
- U0222 Lost Communication With Door Window Motor A Likely for this code Low
- U0224 Lost Communication With Door Window Motor C Likely for this code Low
- U0230 Lost Communication With Rear Gate Module Likely for this code Low
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
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.
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