Cylinder misfires, roughy idle and multiple codes
Thread Starter
Newbie
Joined: Dec 2020
Posts: 11
Likes: 2
2003 Mercedes C240
Cylinder misfires, roughy idle and multiple codes
Hi all -
I’m having some problems with my 2003 Mercedes C240. Occasionally when I’m driving and press the gas hard the check engine light starts blinking and the car starts driving rough at lower RPM’s. It starts having a rough idle. When I turn the car off and turn it back on the problem seems to go away for a bit but comes back.
I read the codes and I’m getting multiple misfire codes and a “throttle/pedal position sensor a high circuit input”. The codes are P0300, P0301, P0302, , P0305, P0123.
Recently had the fuel pump and fuel filter replaced because the fuel pump failed. I’ve changed out the gas pedal because that’s what everything on the forums pointed me to but no change.
can anyone help with how I can diagnose the issue?
thanks in advance!
I’m having some problems with my 2003 Mercedes C240. Occasionally when I’m driving and press the gas hard the check engine light starts blinking and the car starts driving rough at lower RPM’s. It starts having a rough idle. When I turn the car off and turn it back on the problem seems to go away for a bit but comes back.
I read the codes and I’m getting multiple misfire codes and a “throttle/pedal position sensor a high circuit input”. The codes are P0300, P0301, P0302, , P0305, P0123.
Recently had the fuel pump and fuel filter replaced because the fuel pump failed. I’ve changed out the gas pedal because that’s what everything on the forums pointed me to but no change.
can anyone help with how I can diagnose the issue?
thanks in advance!
MBWorld Fanatic!
Joined: Dec 2003
Posts: 3,275
Likes: 236
From: BC, Canada
2003 C230K Coupe Orion Blue
Check your ignition coils. Sounds like multiple failed coils. With that said, did all those codes suddenly appear in one shot, or did they start to appear over the span of a few weeks? Even though it didn't happen to me personally, I've heard stories about multiple ignition coils failing at the same time.
Last edited by slammer111; Feb 13, 2021 at 01:35 PM.
