MCSF P0303 Misfire Solved - Alfa Romeo Forum
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(Post Link) post #1 of 1 Old 16-12-13 Thread Starter
Status: Dave
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Join Date: Oct 2011
Location: United Kingdom
County: Greater London
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156 2.0 JTS

MCSF P0303 Misfire Solved

For two years I had been getting a MCSF on my 2005 156 2.0JTS on cold mornings, anything below about 15 deg. It would come on about a minute after start up and last for a few seconds then disappear, leaving P0300 General Misfire and P0303 Cylinder 3 Misfire codes on the engine management system.

I tried everything that I thought could cause a misfire, new plugs, coils.... even had the inlet camshaft replaced as it apparently had a worn on lobe on cylinder 3. All to no avail.

For some reason a couple of months ago I thought I would try leaving the battery disconnected overnight and voila, no flashing MCSF at all even in conditions that I knew would normally initiate the error.

I checked the load on the battery with everything turned off and found it was drawing about 1 amp so started removing fuses and found the culprit was;
Fuse F10 instruments; interior illumination; clock; car radio; trip recorder reset; alarm; remote control receiver; air conditioner; cellular telephone.

I still couldn't determine what was draining the battery as there were too many things on this circuit and it couldn't be the radio because I had the original radio and there only seemed to be an issue with aftermarket ones draining the battery when turned off.

I eventually thought I would disconnect the radio anyway as it was so easy to do and found it was draining 0.6+ amps despite appearing to be completely off.

That was several weeks ago and the MCSF has not reappeared despite temperatures as low as 2.5 deg. Amazing as I always thought I had a problem with the engine, the radio was literally the last thing I suspected.

So if you are getting the same errors, which appear to be a common issue, give it a go, it may not work for you but it's easy to try and best of all it’s free.

Last edited by DaveW156; 16-12-13 at 16:43.
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mcsf , misfire , p0301 , p0303 , solved

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