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P0301 AND P0303 fault codes

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Old 01 August 2014, 09:48 AM
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Yardz
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Default P0301 AND P0303 fault codes

Morning Everyone

on the way home from work last night the CEL light started flashing at me at around 5k rpm i throttled off and continued to flash then it fully stayed on.

nursed it home got the code reader out and come up with

P0301 Cylinder 1 misfire detected
p0303 Cylinder 3 misfire detected

car seems to be fine at idle and low revs, plugs are less than a thousand miles. is there anything else that could cause it to misbehave like this?
cars a 2001 bug wrx unmodded with 130k

many thanks
Old 01 August 2014, 10:23 AM
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giz1978
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compresion test it and swop the coil pack around to see if the fault codes change cylinder
Old 01 August 2014, 12:15 PM
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Infected by sti
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Neutral position switch possibly faulty
Old 01 August 2014, 12:28 PM
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Originally Posted by Infected by sti
Neutral position switch possibly faulty
Isnt that CEL light but no code stored?
Old 01 August 2014, 12:35 PM
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giz1978
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Originally Posted by Infected by sti
Neutral position switch possibly faulty
alot of the time no cel light at all
Old 01 August 2014, 12:50 PM
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ClassicEddie
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MAF. I had the same thing with the misfire codes, wiped the codes then got the dead MAF code instead. Didn't really need it though as it was obvious! lol
Old 01 August 2014, 02:01 PM
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Yardz
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I cleared the code before I came to work and gave it a good spanking to force it to do it again. But nothing came up?

Is there any definitive way to test NPS and MAF? Also why would NPS through misfire code? How does it work?

Thanks
Old 01 August 2014, 03:13 PM
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ClassicEddie
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Nope, but there's a definitive fix!
Old 01 August 2014, 07:20 PM
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Originally Posted by JDM_Stig
Isnt that CEL light but no code stored?
From what I remember it can throw the cel and other times it won't, also it can show as a misfire code iirc and can vary on cylinders.

I'm not sure if a proper diagnostic tool like the snap-onn scanner we use will pick up the problem on the voltage side of things as it thinks the car is not in a gear.
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