Question

Good day. My name is Dirk van Zyl and I have a workshop here in Cape-Town South Africa.. The problem Im having is a code P033284 knock sensor 1 (CYLINDER BANK 2) has a short circuit to ground. A signal is below the permissible limit.No MIL.

I removed intake and both sets of knock sensors. Inspected all the wires and connector to and from sensors and entire harness. The issue with car is it was at a other workshop for a tune but they found it does not make power. only about 200kw. When they clear codes car makes 350kw and 700nm. The code also goes from current to stored when you cycle ignition and appears only when driving after 2nd gear. Easy driving or full throttle,makes no difference. The way you notice it vehicle gets a slow and bad upshift but does not go into limp mode. It rev's up and you can still drive fast. You only notice the gearshift under full throttle also and the lack of power offcourse. I replaced the sensors.

Cleaned the intake valves of carbon (WAS NOT BAD REALLY). Also carried out a oil change. I would have like to replace spark plugs but it seems the have not been changed yet (VEHICLE HAS 156 000km on clock) and the suppressors are very stuck. I could only remove one and the plug did not look good in my opinion. Unfortunately Mercedes South-Africa does not have stock of suppressors so I did not take the risk in removing the rest for fear of damaging them. The code is still present. The only thing basically I have not done is change the plugs. All values when driving are good,the live data shows knock control when requested and as I said all wires and connectors are good,no damage or chaffing.

The battery and electrics are in good condition,tested and battery good and alternator charging and meets all requirements on live data tests. If you could give me any idea as to something I could look at I would really appreciate it. As I said I have a suspicion it might be plugs as when vehicle is idling when up to temp the engine sometimes feels uneven for me,although on smooth running on idle and loads tests it passes all. Also when I feel that uneven idle and rev engine it makes a big backfire through exhaust,but I disregarded that as Ive seen lots of videos of these types of cars doing the pops and bangs. Currently vehicle is in stock state,not tuned. Owner wants fault code resolved before the tune. Any advice you can give will be greatly appreciated.

Best regards: Dirk van Zyl

Vehicle
Odometer
156 000