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Q: Nothing happens when I push the gas pedal

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My car will not stay on. When I push the gas pedal, sometimes the rpms go up, sometimes they don't. My car ends up shutting off. I received error codes: P0300, P0302, P0104, P0171, and P0174.

I changed the spark plugs, and mass air flow sensor. Car has 3/4 of a full tank of gas. I always use premium. When the engine is running, it runs rough.

My car has 56000 miles.

The P0104 is probably the key. This is a code for the Mass Air Flow circuit. What it means is that the reading from the MAF is not along the lines of what the ECU expects. The 171 and 174 are telling you that the engine is running too lean, so the MAF signal is showing less air moving into the engine than it requires. The 300 and 302 codes are misfire codes, and are probably related to the lean condition. The first thing to check for is any air leak; vacuum lines and air hose connections, (some are under the intake manifold). I see you’ve replaced the MAF, but there could also be a problem in the electrical connector or the circuit itself that is affecting the signal. Diagnosing this problem can get pretty complicated. If you would rather delegate this work, you can contact Your Mechanic to have a technician come out to your home or office and check out your Mercedes and let you know what can be done about it.

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