# Fault Codes P0300/01/02/03



## MarksBlackTT (Nov 29, 2016)

Hi all,

Recently had the dash warning engine light flicker on yellow at 80mph and then go out. Did this a few times but again went out if I slowed down a bit. But yesterday came on and stayed on permanently! Today I connected OBD2 code reader and get P0300, P0301, P0302, and P0303 faults. This seems to marry up with 'Random/multiple cylinder misfire detected'. If anyone else has had this particular issue, I would be grateful for any feedback as to how it was fixed. The car has been running fine at all speeds which is a little confusing. Thanks in advance to anyone who can shed some light.


----------



## alistair.carr (May 17, 2016)

Coil packs, coil packs and thrice coil packs....


----------



## MarksBlackTT (Nov 29, 2016)

Right then, Coil packs it is then! Thanks for your quick response.


----------



## Corrado2TT (Mar 16, 2008)

Hi,

Sounds like what I had - see my post that I updated recently:

viewtopic.php?f=19&t=1397209

It's unlikely to be coil packs if all cylinders are showing misfires. In the end I needed the crank sender and ECU (££££££) but if it's the same issue, maybe you might be lucky and get away with just the sender?


----------



## MarksBlackTT (Nov 29, 2016)

Corrado2TT said:


> Hi,
> 
> Sounds like what I had - see my post that I updated recently:
> 
> ...


Hi mate. Thanks very much for your response. Your symptoms seem to mirror mine exactly. I don't believe it's coil packs/spark plug related as the car starts first time, runs smoothly, is economical, accelerates swiftly etc, etc. In fact everything appears as it should UNTIL I hit exactly 90mph! Then the engine warning light flickers on and off and then goes away when I reduce speed. Repeats the scenario each time car his 90mph exactly. Third or fourth time, light stays on permanently and won't reset. Had the car 6 days now, and it has 3 month warranty. Strongly suspect that previous owner or garage I bought from has erased the fault at least once on a OBD2 plug- in without having problem rectified. :x


----------



## MarksBlackTT (Nov 29, 2016)

alistair.carr said:


> Coil packs, coil packs and thrice coil packs....


Pretty sure it's now NOT coil packs having read Corrado2TT's post.


----------



## MarksBlackTT (Nov 29, 2016)

Update........ Booked into local garage yesterday who had it all day. Confirmed that rear drivers side light cluster was shot and thus had burnt pins. Someone has previously tried to bodge it up! Hooked up to diagnostic machine which simply confirmed 5 error codes concerning misfiring detected in all cylinders! Coil packs checked, wire connections checked and spark plugs unnecessarily changed. Made absolutely no difference. Phoned dealer this morning and made it clear that I'm not happy. Retuned car, 130 mile round trip, and agreed to have new rear light cluster fitted AND send off ECU for refurbishment.Let's hope this will sort it out at last. Only had the car 9 days and now I'm in a Mazda 3 diesel courtesy car!!


----------



## MarksBlackTT (Nov 29, 2016)

Well, finally got my car back today. It has had 4 new plugs, 4 new coil packs, the rear drivers side internal light cluster unit replaced and a refurbished ECU!! All under warranty  . Drove the 65 miles back home without incident, no faults lighting up the dashboard and all seems fine. Long may it last so I can finally enjoy the car. Glad to see the back of the Mazda 3 diesel courtesy car too.


----------



## C00P5TT5 (Jul 10, 2016)

When you say bodged hook up i assume you mean the earth.... I've now got the rear light warning light flashing up even though it's working.

I was going to perform the fix on this video but if it will knacker the ecu i will think again... Is this what was done to yours or does anyone know if this fix is a bad one?


----------



## brittan (May 18, 2007)

C00P5TT5 said:


> I was going to perform the fix on this video but if it will knacker the ecu i will think again... Is this what was done to yours or does anyone know if this fix is a bad one?


This is a fix that works: viewtopic.php?f=43&t=332559
It can also be done as a preventative measure, which is what I did - and it has no ill effect on the ECU.


----------



## C00P5TT5 (Jul 10, 2016)

Cheers brittan, looks like what that video suggested but with your backing i have confidence in the fix.

I thought you left? Glad you haven't... Legend!


----------



## C00P5TT5 (Jul 10, 2016)

I take it the best thing to do would be this fix on both the left and right cluster?


----------



## brittan (May 18, 2007)

Yes, that's what I did using TT-driver's guide. I put some pics on here as I did a couple of things differently.

Here: viewtopic.php?f=19&t=1299345&hilit=earth+rear

I didn't leave, still around like a bad smell.  I just bought a Mk3.


----------



## TT-driver (Sep 14, 2010)

What is happening with those ECU's?

Do they get flooded because of high water in the cowl? Do they get flooded with anti freeze from a leaking temperature sensor? Yes that can happen, coolant leaking through the wire into the CPU box. I've seen it on German television!

I'm curious!


----------



## MarksBlackTT (Nov 29, 2016)

Mmmm, very good points there. Yet another design fault(s)?? German engineering......... phaaaaaffff.


----------

