I've seen gas clusters in cars with a diesel engine. The major differences are the gas clusters have an 'economy,' gauge which works off engine vacuum from the intake and the diesel clusters have a light for glow cycle. One of the members here crossed that line and used the vacuum gauge to track the vacuum pump on his diesel.

The biggest issue will using a gas cluster with a diesel engine is that the speedometer isn't going to be accurate. That happens from daily driving and no abuse since it's near impossible to know the quality of diesel you're getting unless you are really dedicated to purchasing your fuel from a good retailer.

Imo, if there is a ground issue within the cluster it's going to be the ground circuit on the cluster itself. Perhaps removing the gauges and cleaning all the contacts both signal and ground on both the gauges and the cluster housing might be the first step. I believe the FSM identifies the hugh mass of ground wires above the steering column as g102.

The ground on the cluster is in the 8 pin rectangular connector just below the center of the speedometer. Of course the wire is brown so testing the continuity of the brown wire to the g102 location would be a wise place to start.

For clarification, diesel with clog the sending unit in the tank a lot quicker than will gas. A sludge buildup at the bottom of the tank in a diesel car is likely to be one of the issues with gauge problems in a diesel car for that reason. Typically, a diesel car with a clogged outlet screen will 'run out of fuel,' while there is still fuel in the tank. Often the sending unit will feed false information to the gauge making it appear to have fuel when there is none due to sludge buildup on the sensor unit.

Gas cars have much fewer issues with sludge buildup but one which has not been running for long periods will develop issue from amber type buildups if it's left sitting with ethanol in the tank.

That is why I wanted to know the exact designation of your car. I suppose most people here would felt as if they were fools trying to help you without sufficient information. Fuel gauge issue.

As for the oil gauge, the most common problem is a loose wire on the oil sending unit. Figuring out if that is the issue is usually as easy as wiggling the connector on the sending unit with the engine running and having someone tell you if the needle on the oil gauge is jumping around.

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84 300SD
85 380SE
83 528e
95 318ic