SLC Diesel Check Engine Light and Fuel Consumption

VANOS failure on these isn't unheard of. I had a similar problem with my SLC, though I didn't get the check engine light immediately. Higher fuel consumption was the first sign. It turned out to be the VANOS solenoid. Before jumping to conclusions, have you checked for any signs of oil sludge? That can definitely mess with the variable timing and cause the VANOS solenoid to malfunction. Is the check engine light constant, or does it come and go?

Thanks for the quick reply! I haven't specifically checked for oil sludge myself. Where exactly should I be looking for that? And regarding the check engine light, it's intermittent. It comes on for a day or two, then disappears for a few days, only to reappear again. When you had the VANOS solenoid issue, did the fault code specifically point to that, or was it more general?

Okay, intermittent check engine light and increased fuel consumption definitely point to a potential VANOS solenoid issue, especially if it's related to variable timing. Honestly, checking for oil sludge properly often involves removing the valve cover. If you're not comfortable doing that, I'd advise against it. Given your symptoms and the error code you got, it's likely a faulty VANOS solenoid or an issue with its power supply, as initially suspected. Given the potential complexity and need for proper diagnostics, I would suggest going to a workshop.

Thanks a lot for the help! I took your advice and went to a workshop. Turns out it was a faulty VANOS solenoid, just like you suspected. They replaced it, and the check engine light is gone, and the fuel consumption is back to normal. The final bill was pretty much what I expected, so no surprises there. Appreciate the guidance!