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Discussion Starter · #1 ·
My 03 Mazda 6s has been running great for me and has almost 62k miles on it. Twice this weekend it threw a CEL while accelerating onto a highway. The code that's on the paperwork is 'P0304', which my dealer claims is the 4th ignition coil misfire. They won't replace the coil yet though, because my remote start is supposedly connected to that coil. They want me to run the car for two weeks with the remote start disconnected to see if I get another CEL.

Now I didn't get the remote start installed at the factory, but I got the next best thing. I happen to work for the company that produces alot of the OEM parts for Mazda, Ford, Toyota, etc. and we happen to make the remote start for the 6. Long story short, one of the engineers that helped design it and a factory certified tech installed it for me, so there should be no issue at all with the remote start.

My question is this though, they reported that it was the 4th coil that had the remote start attached and that was one to had misfired. I looked the code up on the Mazda6Tech site and it says that the code indicates a 5th coil problem 'P0304 Cylinder No.5 misfire detected Flash / ON 1 or 2 Misfire'.

Are they just trying to blame this on the remote start because they can, or could this be a real problem with it. Sounds to me I just need a new coil.

Plus, they said that since they didn't replace the coil my the labor is not covered under my extended warranty (I'm covered till 75k), so I was charged $150 just to look at this issue.

PS - After the reportedly "disconnected" my remote start, I can still remote start it. I called them about it they said that's not unnormal, that they taped the connector to the firewall and to just not remote start it. I think I'll have one of the techs here take a look at it tomorrow to see exactly what they did.

UGHH

Any thoughts on this situation, sorry just needed to vent a little.
 

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they are just jerkin ur chain cuz they dont want to do the replacement under warranty. Ive gotten this cel before but tahts because i didnt let the car warm up fully before gunning it.. it will flash for a few times then stay lit rite? how long have you been driving before u gun it to get on the highway? when i start my car in the morning i let it warm up atleast till the temp needle gets passed the first bar. and by the time i get anywhere wher ei need to gun it the engine is fully up to temp...
 

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Discussion Starter · #3 ·
they are just jerkin ur chain cuz they dont want to do the replacement under warranty. Ive gotten this cel before but tahts because i didnt let the car warm up fully before gunning it.. it will flash for a few times then stay lit rite? how long have you been driving before u gun it to get on the highway? when i start my car in the morning i let it warm up atleast till the temp needle gets passed the first bar. and by the time i get anywhere wher ei need to gun it the engine is fully up to temp...
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The engine was def warmed up both times when i pushed it hard to get on the highway. Just like you said, the CEL flashed for a few then went solid.

Taking it on a long trip this weekend, see what happens then i guess...
 

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This is a subject im an expert on. I had 30+ Cel for that same problem, which was the same code as yours, but my dealership was very nice. Tell them to contact the Mazda Engineers and tell them whats going on. It is trapped exhaust gasses causing the CEL under hard acceleration, then letting off ...boom..CEL. I even met with the Mazda Eastern Regional rep (great guy) he asked me to be patient. A short time later I received new exhaust manifolds, that looked bored out , they were for sure bigger than the stock ones. After they were replaced I have never had a CEL since then. So dont let them BS you , this is a big problem. My car was put through alot of test and even used as a test subject so to speak to deal with this problem.
 

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Discussion Starter · #5 ·
Blaze, thanks for the info, I'll be sure to point that out to the dealer when I see them next.

Like I said in my previous post, I work for the company that produces these things for Mazda, so I grabbed the engineer that works with these and he took a look at it. It turns out the the cable the dealer thought was causing all these problems and therfore disconnected was never connected to anything on the other side and then obviously couldn't be causing a problem. The engineer said they hooked it up that way initially and then decided to do it a different way.

Instead of me trying to rationalize with the dealer now, my guys at work are going to call their contacts at Mazda Corporate to try to get my money back. It also turns out a few of the other techs used to work at this dealer, so they're going to speak with them as well. Hopefully, one way or another this will get resolved and my car will fixed properly.

Disconncected cable...ugh
 

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I would follow the dealers advice at least for now and remove the remote start. I too had the PO304 code pop up a few times accompanied by a noticeable engine stutter. After hearing about the problem that copper6 had, I was worried that it was a major problem.

As it ended up, my dealer replaced the coil under warranty. Almost two years later, I have not had a recurrence of that cel code. Removing the remote start sure sounds like a valid trouble shooting procedure to me. I imagine that if the code persists, the next thing they'd want to do is replace the coil and test drive the car. If the code still comes up, then you will want to look into what copper6 mentioned.

It could just be that you have a bad coil or that the remote start is temporarily fouling the coil. Just a heads up, given that you have an aftermarket part linked to that particular coil, you may have a hard time getting it replaced under warranty - at least from that dealer given that they know about your remote start.

If that's the case, perhaps you can get some assistance from the people that designed and installed the remote start.

Good luck.

Edit:
I just saw that you mentioned the remote starter is not connected to the coil. In that case, the dealer should replace the coil under warranty to see if that fixes the problem.
 
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