Audi A4 B5 Comfort Control Module Faults Common Failures and Repair
The comfort control module on the Audi A4 B5 — known internally as the Komfortsteuergerät — is responsible for central locking, electric windows, interior lighting, and mirror folding. When it fails, you typically get a combination of dead window switches, central locking that works intermittently or not at all, and dome lights behaving strangely. It is one of the most frequently replaced modules on late-1990s and early-2000s A4s, and the failure pattern is well documented among independent Audi specialists.
Most owners first notice something is wrong when one or more electric windows stop responding to the door switch, or the central locking only locks some doors. The module sits behind the driver-side dashboard trim and is directly exposed to moisture intrusion — particularly from a leaking windscreen seal or blocked scuttle drain — which accelerates corrosion on the PCB connectors.
What Are the Most Common Symptoms?
- Central locking operates only partially — one or two doors fail to lock or unlock
- Electric windows unresponsive from the master switch but working locally at each door
- Interior dome light stays on permanently or does not illuminate at all
- Mirror folding function stops working
- Alarm system false triggers or fails to arm
- Key remote (433 MHz) stops being recognised even after battery replacement
- Window auto-close function (on sunroof variants) no longer works
What makes this module tricky is that the symptoms often develop gradually. You might have one stiff window for months before everything collapses. Some owners replace door switches, window regulators, and even door lock actuators before the module is correctly identified as the root cause.
Why Does the B5 Comfort Module Fail?
There are two dominant failure modes. The first is moisture damage — water gets into the driver footwell or travels along wiring looms, and the module absorbs enough humidity to corrode its internal relay contacts and PCB tracks. The second is heat cycling. The module is mounted close to the heater box and goes through thousands of thermal cycles over the years, which eventually causes solder joint fatigue, particularly around the relay and capacitor legs. For comparison, see Audi A4 B5 Instrument Cluster Failure: Common Faults and Repair.
On very high-mileage examples — 250,000 km and above — you also see the internal relays simply wearing out mechanically. They click thousands of times per year and eventually stick closed or fail to switch. When a window relay sticks closed, the window motor runs against the rubber stop continuously and can burn itself out, so catching the module failure early saves a second repair bill.
Common Error Codes
| Fault Code | Description |
|---|---|
| 01267 | Comfort system — open or short circuit in control module |
| 01044 | Control module incorrectly coded / adaptation not carried out |
| 00532 | Supply voltage — implausible signal (module not receiving stable voltage) |
| 01176 | Central locking pump — no signal from comfort module |
| 00588 | Driver window motor — open circuit |
| 01257 | Interior monitoring sensor — signal missing |
Code 01044 is worth noting specifically — it appears after a replacement module is installed but before it has been coded to the car. A fresh used OEM unit must always be adapted using VCDS or a compatible VAG diagnostic tool, otherwise the remote key and central locking will not function correctly even with a perfectly good replacement.
Common OEM Part Numbers
The correct part number depends on the exact build date, body style (saloon, Avant, or Cabriolet), and whether the car has a sunroof. Always cross-reference against the sticker on the original module before ordering.
- 8D0 962 258 C — standard saloon/Avant, central locking pump system, pre-facelift
- 8D0 962 258 H — facelift model (1999–2001), revised relay layout
- 8D0 962 258 L — late production, sunroof variant
- 8D0 962 258 F — Cabriolet body-specific coding
- 8D0 962 258 A — early B5 production (1995–1997), fewer functions
- 8D0 962 258 K — Avant with trailer module integration
If you source a tested used OEM unit, confirm the last letter suffix matches your original, or verify compatibility by part number cross-reference. GiantParts stocks tested B5 comfort modules pulled from verified donor vehicles, checked before dispatch. A related diagnostic guide is Audi A4 B5 ABS Control Module Failure: Symptoms and Repair Guide.
Affected Vehicles
- Audi A4 B5 Saloon — 1995 to 2001
- Audi A4 B5 Avant — 1996 to 2001
- Audi A4 B5 Cabriolet — 1998 to 2002 (shares platform electronics)
- Audi Passat B5 (VW) — shares the same module family; 8D0 coding applies on some early variants
- Audi S4 B5 (2.7T) — same comfort module; higher mileage typically reached faster
Diagnostic Steps Before Replacing
Before spending money on a replacement, do these checks first. Pull a full VCDS scan of the comfort module and note every stored fault — even historic ones. Then check the module connector for visible corrosion or bent pins; a poor pin-to-socket connection on connector T10b or T10a causes exactly the same symptoms as a dead module. Spray connector cleaner and reseat the plugs — sometimes this alone resolves the fault temporarily.
Check the fuse allocation too. Fuse 23 (10A) and fuse 42 (15A) in the B5 fuse box feed the comfort module directly. A blown fuse from a previous actuator short can mimic a dead module completely.
If fuses and connectors check out, the module itself needs replacement. Repair is possible in specialist workshops — relay replacement and PCB resoldering can revive a moisture-damaged unit — but turnaround time varies and success is not guaranteed on heavily corroded boards. For most independent garages, a tested used OEM unit is the faster, more reliable path.
Frequently Asked Questions
Can I replace the Audi A4 B5 comfort module myself?
The physical swap is straightforward — the module clips behind the driver-side lower dash trim and connects via two multi-pin plugs. The harder part is coding: after fitting a used unit you must carry out basic adaptation using VCDS or a compatible VAG-COM interface. Without this step, the remote key will not sync and the locking system behaves erratically. If you own a VCDS cable and have basic diagnostic experience, the full job takes about an hour.
Why does my A4 B5 central locking work sometimes but not always?
Intermittent central locking on the B5 almost always points to a comfort module relay on its way out, or a corroded connector. Cold weather makes it worse because corrosion becomes more resistive at low temperatures. Scan for fault code 01176 or 01267 to confirm module involvement before chasing actuators or wiring. For additional context, read Audi A4 B5 Instrument Cluster Faults: Common Failures and Repair.
Does fitting a used comfort module require special coding?
Yes — every replacement comfort module on the B5 platform requires basic settings adaptation in the comfort module channel using VCDS. The procedure sets the window pinch protection limits and syncs the remote key. This does not require matching the VIN; it is a functional adaptation, not an immobiliser pairing. Any quality VCDS cable and free VCDS Lite software is sufficient.
What is the difference between the early and late B5 comfort module?
Early modules (1995–1997, suffix A/B/C) handle fewer functions and use a simpler relay configuration. Facelift modules (1999 onward, suffix H/K/L) added sunroof one-touch, revised window auto-down memory, and sometimes trailer socket signalling. Mixing generations causes coding errors and non-functioning features, so always match the suffix letter or verify cross-compatibility before fitting.
How much does a tested used OEM comfort module cost compared to new?
A new OEM module from Audi/Bosch supply chain typically costs €180–€280 depending on variant. A tested used OEM unit from a reputable European supplier runs €40–€90 and, when properly coded, performs identically. The key word is tested — modules sold as untested salvage carry a meaningful risk of arriving with the same fault as the one you removed. GiantParts tests and verifies modules before shipping worldwide.
Find tested OEM electronic parts and modules at:
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