Alfa 156 Diesel Fuel Filter Heater Draining Performance

Last month I dealt with nearly identical symptoms on my 2005 Alfa 159 JTD. The rough idle and power loss started gradually, but the fuel consumption increase was quite noticeable within a week. After inspection, it turned out the fuel filter heater connection had corroded, causing intermittent electrical contact. The poor connection was making the fuel filter system malfunction, leading to inconsistent fuel pressure and the performance issues. The repair involved replacing both the fuel filter and its heating element, plus cleaning and resealing the electrical connections. This was actually a fairly serious issue since prolonged running with improper fuel heating could have damaged the injection system over time. The fix restored normal power delivery and resolved the rough idle completely. Fuel consumption returned to normal after about 2 tank fills. Would strongly recommend having the entire fuel line system checked while the filter is being replaced, as these issues often come together in these models. Make sure your mechanic checks the wiring harness connection points specifically, as this is a known weak spot in the fuel heating system of these engines.

Thanks for the detailed reply on my Alfa issue. Had exactly the same symptoms with cold start problems being especially noticeable. My diesel engine definitely feels smoother since fixing it and fuel consumption is back to normal. Just wondering roughly how much the repair cost you? Also curious if you had any other fuel system issues pop up since getting it fixed?

Got my Alfa back from the shop last week after the fuel filter heater repair. Total bill came to 95 Euro for fixing the faulty cable connection, which was causing all those power loss issues. The mechanic found the plug connection was deteriorated and needed cleaning plus proper reseating. The diesel engine runs much better now, no more rough starts or irregular performance. Fuel efficiency is back to where it should be. Really glad I got it sorted quickly since running with a malfunctioning fuel system could have led to bigger problems down the line. No other fuel line issues have shown up since the repair. The mechanic did a thorough check of the entire fuel system while fixing the heater connection, which gave me good peace of mind. Definitely worth having that comprehensive inspection done when these symptoms appear.

Following up on this thread, I finally got the Alfa fixed last week. Found a reputable mechanic who actually specializes in fuel system diagnostics. The final diagnosis matched what others described, corroded fuel filter heater connections causing all those issues with power loss and rough running. Total repair came to 180 Euro, bit more than expected but included a complete fuel filter replacement and thorough fuel line inspection. The cold start problems disappeared immediately after the fix. Fuel efficiency is already much better after just one tank. Really glad I asked here first and knew what to tell the mechanic to check. Saved me from another potentially bad repair experience. The engine runs smoother than it has in months, especially during morning starts.