Hi guys... sorry to bring up another thread for a p0303 fault code, ive looked at all the other threads on this forum and none are seeming to go as far as mine with regards to a process of elimination based on this code and past changing coils and spark plugs with an odd mention of injectors. Im wondering if anybody has actually successfully cleared this code.... but not by the regular coil changes and spark plug change.

 

My sinarieo is this. Please bare with me......

 

My issue started 5 months ago when i experiance on 2 seperate occasions over a 2 week period i had some very bad misfiring and ruff idling upon start up from cold. Both occasion the engine light flashed up but also cleared quite quickly, as did the ruff idling/running when i persisted to throttle the car through the ruffness. After the second occasion I decided to contact a friend who owns a vag dianostic machine. He plugged my car in and it brought up a p0302 intermittent misfire cylinder 2 fault (common fault code i know). In short we cleared all the codes, but not before having a fiddle with the harness and connections as well a re-seating the coils just incase they've lifted excessively off the plugs, either due to vibration over time or knowing id already replaced my sparks plugs 8000miles previously and possibly they hadn't  been reseated correctly by my mechanic at the time, either way im happy the plugs are fine being so new, where as my coils are original at 70k as far as i know. The plugs i installed at the time were Denson Iridiums plugs - £80 for 4.  Now from here i actually didnt have another problem relating to this until 3 months later when i actually broke down on a journey in the car. I was driving quite happily round the country lanes when suddenly i had some misfiring happen, i pulled over streight away and switch the car off... i then proceeded to pop the hood up and pushed down on all my coils, which all dropped about 1 - 2mm ( infact when i did my fiddle above ^ they dropped about the same then too ) .. anyway i then went to restart the car, it cough n spluttered and kick out a huge cloud of white-ish smoke from the exhaust, i immediately stop trying to start the car and at that point and my worse nightmares flashed before my eyes... i let the car sit for about 20min while i was scratching my head thinking @#$! NO!!!!....lol, i then went to start it again.... and it started, though very ruff at first it did sort itself out and began to idle and rev fine within a minute and no smoke at all, sounded perfect. I even continued a 15 mile journey with no more problems. But still i contacted my buddy again, we plugged in and again we had the same fault a p0302. So now on the strength of this i decided to replace the coils as im still confident my spark plugs are ok being so new. I purchased 4 new Bosch coils at £115 with a £70 saving from a promo....Sweet deal i felt!!.  I fitted these new coils 2 weeks ago. At the time when i fitted them i didnt have any new misfiring happening and all was running fine, so i actually  didn't notice any change in drivability or anythink for that matter once id fitted the new coils, until yesterday that is.... my car was up to temperature, and i had driven it about 2 miles from my home when i experianced some hesitation under low acceleration along with my engine light which flashed on for 10 to 15 seconds then everythink cleared including the engine light and car returned to normal and seemed to run fine. So today i decided to pull my spark plugs out and have a look at them, i was first suprized to find my baby daughter would have had the strength to loosen cylinder 2's spark plug yet the rest were about as tight as id expect them to be...  this suddenly give me a small light bulb moment where i thought well a sloppy plug in cylinder 2 which is the cylinder showing a fault everytime, i felt id possibly stumbled across the root cause to all this... but and a big BUT! I had my buddy plug in again today as well and to my amazment and shock its now reading a p0303 intermittent misfire cylinder 3.... please Note cylinder "3"  and not 2 which it has been the whole dame time, yes the misfire has moved. Codes are once again cleared and sparks are tightened correctly. Where do i go next?????

 

HELP ME PLEASE!!! Thoughts, ideas, anythink... what should be next in my process of elimination. Coil harness connections? Injectors? Anythink cheaper than injectors to try first?

 

Appologise for the long read btw, and i do hope ive been clear enough for you to understand how events have panned out and i havent just rambled. Heres a summary....

 

What ive done so far.....

 

*New spark plugs fitted 8k before first n second misfire detections. Reseated original coils at the time and cleared fault codes.

 

*New coils fitted after the 3rd detection which was 3 month after the 1st detection came up. Fault codes cleared again.

 

*Fault has now jumped from cylinder 2 to 3 following the coils being changed 2 weeks ago. Reseated spark plugs today and when i unscrewed them i found Cylinder 2 was not tight enough, completely effortless) Codes cleared once again.

 

* If fault re-occurs now, i can eliminate all the above plus spark plugs not being tightened correctly. 

 

Thanks for a taking the time to read this... lol hope ya didnt fall asleep

 

Ive just experience something similar however my car hasn't spluttered yet However I experienced the same as you with the CEL light flashing then going off. Today It started flashing and is now on constantly.

 

I also changed the sparks a few months ago and haven't had a problem since then.

 

I have the following fault but can't seem to clear them!  I've just changed the Coil pack No3 and now Im going to take for a run.  

 

001089 - EVAP Emission Control Sys 

               P0441 - 000 - Incorrect Flow - Intermittent

             Freeze Frame:

                    Fault Status: 00100000

                    Fault Priority: 0

                    Fault Frequency: 1

                    Reset counter: 255

                    Mileage: 197947 km

                    Time Indication: 0

                    Date: 2025.14.13

                    Time: 08:14:36

 

             Freeze Frame:

                    RPM: 759 /min

                    Load: 13.3 %

                    Speed: 0.0 km/h

                    Temperature: 98.0°C

                    Temperature: 44.0°C

                    Absolute Pres.: 990.0 mbar

                    Voltage: 13.843 V

 

000771 - Cylinder 3 

               P0303 - 000 - Misfire Detected - Intermittent - MIL ON

             Freeze Frame:

                    Fault Status: 10100000

                    Fault Priority: 0

                    Fault Frequency: 2

                    Reset counter: 255

                    Mileage: 198830 km

                    Time Indication: 0

                    Date: 2025.14.29

                    Time: 08:13:25

 

             Freeze Frame:

                    RPM: 3965 /min

                    Load: 100.0 %

                    Speed: 108.0 km/h - Bizarre!

                    Temperature: 93.0°C

                    Temperature: 13.0°C

                    Absolute Pres.: 990.0 mbar

                    Voltage: 14.097 V

I changed my coil pack for cylinder 3 over the weekend and cleared the fault codes via the xtool app via a plug in obd2 module as I couldn't seem to clear it via VCDs! 

Anyway good news is that I've driven to work and no fault code. 

 

Try changing the coil pack as it maybe on its way out!