Gas and temp gauge not working - 318i BMW Cars & Trucks

The gauges should get power from the same circuit. So if the gas gauge works, the temp gauge should have power.
Could be the sending unit on the engine, or the gauge itself.

check the fuse block for a blown fuse, the one that controls dash gauges should be identified in the owner's manual.

check for a common fuse( Instrument panel)

If none of the gauges work, there is a power problem.
The gas tank sender grounds the fuel gauge and the temp sender on the engine block grounds the temp gauge.
Could be a wiring harness issue or a problem with the printed circuit board too.

Maybe I can help a little they are right it is one unit. How ever each one has a sendding unit and are fused. Your temp gauge has a sendding unit your speedodomder works off a cable. I'm resorring my first car 87' camaro none of the gauge work ex. the speed. No gas, no temp or oil replaced sending units they work now but they not cheap. I got tried of running uot of gas I'm a bad guesser.

Hope I answered your proplem.

sensor might be malfunction of the circuit might be disconnected.

sounds like a fuse

check fuse box,under your dashboard or hood.look for small print,that indicates the fuse operations

check with GM on a recall

as far as the temp gauge goes...i have a 91 1500, i had the same problem. i replaced the temp sensor and it fixed the problem.

as far as the bad gas mileage... if you haven't already done so, perform a tune up; plugs, wires etc.