Alfa 147 Auto Gearbox Failure: Rough Shifts & Slip Alert

Had nearly identical symptoms with a 2004 Alfa 156 2.0L. Being somewhat experienced with transmission issues, I initially thought it was just a fluid problem too. The diagnostic trouble codes revealed that erratic gear selector behavior and limp mode activation were actually triggered by faulty ABS sensors feeding incorrect data to the transmission control unit. The traction control system was getting confused signals, causing the transmission to behave unpredictably. The workshop confirmed multiple sensor faults in the ABS system were causing these transmission symptoms. Since the ABS unit was still under extended warranty, the repair cost nothing. They replaced the ABS sensor cluster and recalibrated the system. Before suggesting specific fixes, could you share: Current mileage, Any recent repairs or maintenance, Whether your check engine light is on, If you notice any unusual sounds from the wheels, Whether the issues get worse in wet conditions, If the ABS warning light ever comes on This information would help determine if your issue matches what I experienced or points to something different.

Had my latest service done 3000 km ago at 99320 KM. After your reply, I checked and yes, the ABS light does occasionally flash along with the check engine light. That lines up with what you described. The torque converter behavior definitely gets worse in wet conditions, which seems to support your theory about the ABS sensors affecting the powertrain malfunction. The control module might indeed be getting confused signals. Before scanning for fault codes, I will check the wheel sensors since they are a common failure point that could trigger these transmission problems. The garage quoted 450 Euro for a full diagnostic check of both systems. The limp home mode activates mainly during cold starts now, which seems consistent with sensor-related issues rather than mechanical transmission problems.

Thanks for providing those details. Those symptoms sound even more similar to what I experienced. When my Alfa 156 showed those exact patterns, transmission issues in wet conditions and cold starts triggering limp mode, it was definitely the ABS sensors interfering with the powertrain system. Before spending 450 Euro on diagnostics, you might want to try cleaning the wheel speed sensors first. Road grime build-up can cause similar fault codes and gear selector issues. The key signs pointing to ABS sensors rather than actual transmission problems are: Limp mode mainly during cold starts, Worse performance in wet conditions, Both ABS and check engine lights appearing, Issues starting after recent service The transmission control unit in these models is highly sensitive to incorrect wheel speed data. When my ABS sensors were failing, the powertrain malfunction warnings would come and go out of nowhere, especially during weather changes. A simple sensor cleaning might resolve it, but if not, budget around 300 Euro for new sensors plus labor. Much better than a full transmission repair.

Thanks for the detailed response about the sensor connection to transmission problems. After getting your reply, I did some research and checked online repair forums, multiple Alfa owners reported similar symptoms fixed by replacing ABS sensors. The wheel sensors showing wear matches my car's age and mileage. Going to try cleaning them first before the diagnostic appointment. Having both the ABS and transmission warning lights appearing in cold and wet conditions does suggest sensor problems rather than serious transmission damage. I will give the garage these details about fault codes potentially being triggered by faulty ABS sensors affecting the control module. Hopefully they can confirm if this is causing my transfer case and gear selector issues before doing any major transmission work. If cleaning doesnt help, at least replacing sensors would be much cheaper than rebuilding the transmission. Will update once I know more. Again, really helpful to hear about your similar experience with the limp home mode and sensor-related fixes.