VW Lupo Timing System Causing High Fuel Usage

I experienced similar symptoms on my 1999 VW Polo with the 1.4L engine. The check engine light came on and fuel economy dropped noticeably. After diagnostics, it turned out to be a faulty inlet camshaft VANOS solenoid causing improper variable timing operation. The solenoid failure was preventing proper oil flow control to the camshaft actuator, leading to engine misfire issues at certain RPMs. This is a known weak point in these engines, when the solenoid starts failing, it affects the entire variable timing system performance. This was a serious issue requiring immediate attention since continued driving could have caused additional engine damage. The repair involved replacing both the VANOS solenoid and cleaning the oil passages to ensure proper function. The symptoms you describe match exactly what happened in my case, increased fuel consumption combined with the check engine light is a classic sign of variable timing problems. Would recommend getting it diagnosed properly with a scanner that can read VW-specific codes before replacing parts. A qualified mechanic should first verify if its the solenoid or perhaps just a wiring issue, as sometimes the power supply to the solenoid can be interrupted due to corroded connections.

Thanks for sharing your experience with the VANOS solenoid issue. Just went through something very similar with my 2002 Lupo last month. The timing system problems really hit the fuel consumption hard and that check engine light was driving me crazy. Curious, do you remember roughly how much the total repair ended up costing you? I paid about 380€ for my fix but wondering if that was reasonable. Also, has everything been running smoothly since the repair or did you notice any other issues pop up related to oil sludge buildup in the system?

Had the repair done last week and can confirm it fixed the VANOS issues completely. The total came to 250€ which covered replacing the faulty inlet camshaft solenoid valve. The mechanic found one of the VANOS solenoid valves was defective, causing the variable timing system to malfunction. Fuel consumption is back to normal and the check engine light hasnt come back on. The mechanic also checked for oil sludge buildup while doing the work but found the oil passages were actually quite clean. No additional issues have shown up since the repair. Your 380€ repair cost seems reasonable since prices can vary based on parts availability and labor time. The important thing is the variable timing system is working properly now, these VANOS failures can cause serious engine damage if left unfixed. Regular oil changes with the correct grade oil should prevent future problems with the VANOS solenoid and camshaft components. The system relies heavily on clean oil flow for proper operation.

Thanks everyone for the helpful replies. Finally got the car back from the shop yesterday after dealing with the VANOS system issues. The mechanic found the inlet camshaft solenoid was completely clogged with oil sludge, causing the variable timing to malfunction. They cleaned out all the oil passages and replaced the faulty solenoid. Total bill came to 380€ which included parts and labor. Since the repair, the check engine light has stayed off and I can already tell the low power issues are gone. Fuel consumption is back to normal levels too. What really helped was going in knowing what to expect thanks to the advice here. The mechanic confirmed everything you all mentioned about these common VANOS failures. They recommended regular oil changes to prevent future buildup. The car runs like new again.