HELP camshaft sensor fault/missfire
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Scooby Newbie
Joined: Oct 2017
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From: uk
HELP camshaft sensor fault/missfire
Hey guys
For past week or so i keep getting code P0340 & P0301
on my05 sti uk spec, symptoms are misfire & seems a bit slow/lazy to start
after searching on forum its one of the following
bank 1 cam sensor, coil pack or NPS, i did remove cam sensor gave it a clean
but faults back after few days, what should i change first ?
many thanks
For past week or so i keep getting code P0340 & P0301
on my05 sti uk spec, symptoms are misfire & seems a bit slow/lazy to start
after searching on forum its one of the following
bank 1 cam sensor, coil pack or NPS, i did remove cam sensor gave it a clean
but faults back after few days, what should i change first ?
many thanks
Scooby Regular
Joined: Feb 2003
Posts: 7,841
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From: Harpenden
Other possibilities
P0340
It could also be your alternator........... post #31
https://forums.nasioc.com/forums/sho....php?t=2786898
P0301
https://forums.nasioc.com/forums/sho....php?t=2333222
P0340
It could also be your alternator........... post #31
https://forums.nasioc.com/forums/sho....php?t=2786898
P0301
https://forums.nasioc.com/forums/sho....php?t=2333222
Thread Starter
Scooby Newbie
Joined: Oct 2017
Posts: 13
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From: uk
P0301 has returned first
multi meter is showing 12.50V with car running
Other possibilities
P0340
It could also be your alternator........... post #31
https://forums.nasioc.com/forums/sho....php?t=2786898
P0301
https://forums.nasioc.com/forums/sho....php?t=2333222
P0340
It could also be your alternator........... post #31
https://forums.nasioc.com/forums/sho....php?t=2786898
P0301
https://forums.nasioc.com/forums/sho....php?t=2333222
Scooby Regular
Joined: Feb 2003
Posts: 7,841
Likes: 834
From: Harpenden
Seems a bit low, (should be around 14V) but it's not the voltage it makes, it's the "noise" that it can generate that can cause a problem with sensor signals.
The thread post I referred to..............
The thread post I referred to..............
so i unplugged the alternator and reset the ECU. started the car up and....no CEL. plugged the alternator back in and sure enough, immediately got the CEL (P0340).
so i swapped out the alternator for a new one, started the car up and no CEL. Voltage at the alternator and battery under load is reading 14.2 volts. so in the end, it appears that indeed, a bad alternator can truly cause the P0340 code. apparently a bad diode or voltage regulator sends a noisy signal through the harness and the cam sensor reads this as a fault.
so anyone experiencing this code and has the primary symptoms of momentary rough idle especially when the AC is turned on, please check the alternator. it may appear to be sending proper voltage or even pass testing, however internally its faulty and is tripping the CMP. for people who have a no start situation with this code, your actual sensor may be bad, faulty wiring, bad ECU or skipped timing.
so i swapped out the alternator for a new one, started the car up and no CEL. Voltage at the alternator and battery under load is reading 14.2 volts. so in the end, it appears that indeed, a bad alternator can truly cause the P0340 code. apparently a bad diode or voltage regulator sends a noisy signal through the harness and the cam sensor reads this as a fault.
so anyone experiencing this code and has the primary symptoms of momentary rough idle especially when the AC is turned on, please check the alternator. it may appear to be sending proper voltage or even pass testing, however internally its faulty and is tripping the CMP. for people who have a no start situation with this code, your actual sensor may be bad, faulty wiring, bad ECU or skipped timing.
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Thread Starter
Scooby Newbie
Joined: Oct 2017
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From: uk
Swapped coilpacks around & charged battery which looks like it's not holding charge fully
as when I discount ctek charger then reconnect it takes approx 20/30 mins to reach full charge again
took car for drive & code P0301 misfire cyl 1 has come back
so can't be coilpack, plugs are new, could it be that timing has slipped few tooth ?
last timing belt was changed over 4 yrs ago around 44k
current mileage is 76k
as when I discount ctek charger then reconnect it takes approx 20/30 mins to reach full charge again
took car for drive & code P0301 misfire cyl 1 has come back
so can't be coilpack, plugs are new, could it be that timing has slipped few tooth ?
last timing belt was changed over 4 yrs ago around 44k
current mileage is 76k
Try a new battery first boss you wouldn't believe with modern day vehicles especially diesels the effects that even a half knackered battery has. It might turn over and start 100% but if its short of power volts or current things go t*ts up.
Thread Starter
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From: uk
nice one pal, got a spare battery so will try that.
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Thread Starter
Scooby Newbie
Joined: Oct 2017
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From: uk
