# 1999 Jetta AEG 2.0L is misfiring



## rabbott73 (May 20, 2010)

Hello, the other day my daughter's check engine light came on - she drove it for a day without any problem but the check engine light was still on. The next day it started randomly cutting out mainly at stop signs and running badly at times (it only happens occasionally). 

I took the jetta to autozone and got the following fault codes.

P0118 - Engine coolant temperature (ECT) circuit high
P0300 - Random cylinder misfire detected
P0302 - Cylinder 2 misfire condition
P0303 - Cylinder 3 misfire condition

I put some injector cleaner in and ran it for a few days without any luck. Still the same codes and being very sluggish at times. Before I go start buying parts (plugs, plug wires, etc) I thought I would post the codes to see if anybody could narrow the problem down. Since it only happens occasionally I was wondering if maybe the ECT sensor went haywire.


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## Jay-Bee (Sep 22, 2007)

ECT is a common failure item.

Go buy a new one, make sure it's a "green top", older ones had many issues, I doubt any places still have the black one in stock anymore but just in case.

That sensor can cause misfires, it's only 20 bucks even at a dealership and it's a 5 minute job tops (you will lose a bit of coolant)

If you feel like doing plugs as well they are a little pricey but last a good while. NGK BKUR6ET-10 for them... and if you really want to go all out and get wires stick to an OEM brand name... I use Beru, but there are other.

All depends on what the service record is like for this Jetta.

cheers


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## rabbott73 (May 20, 2010)

OK Thanks Jay, I'll pickup an ECT sensor this evening and give it a try. I'll post my findings.

Thanks


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## rabbott73 (May 20, 2010)

I put in the new ECT sensor and the check engine light is remaining on. I took it for a test drive anyways for about 20 minutes with no misfiring. I had my daughter drive today so we'll see if she experiences any misfires. I'm going to take it up to autozone this evening and get the fault codes again. Could it possibly be that the computer just needs reset?


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## Jay-Bee (Sep 22, 2007)

rabbott73 said:


> I put in the new ECT sensor and the check engine light is remaining on. I took it for a test drive anyways for about 20 minutes with no misfiring. I had my daughter drive today so we'll see if she experiences any misfires. I'm going to take it up to autozone this evening and get the fault codes again. Could it possibly be that the computer just needs reset?


No need, after a bit of driving it will reset it self. I don't think Autozone will clear codes, only read them, give it a day, it should turn off if it detects everything is fine.


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## rabbott73 (May 20, 2010)

Well false alarm. The misfiring continues. I didn't get a chance tonight to run it to autozone to get the codes checked again. Will do tomorrow. Any other suggestions?


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## rabbott73 (May 20, 2010)

OK, after replacing the ECT sensor with it still misfiring, i had the codes read again. This time I got the 302,303 misfiring codes and a new one PO422 (I believe) it was something to do with the catalytic converter threshold. Atleast the ECT sensor code didn't show up .

Also, within the last few days or driving it - the CAT is making a bunch of rattling noise inside the pipe (it's not the shield)....Do you think that could have been my problem all along. I'm wondering why the PO422 error didn't show up prior to me replacing the ECT sensor.

I appreciate the help.


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## rabbott73 (May 20, 2010)

I changed the spark plugs last night - they didn't look to bad when I pulled them off but I replaced them anyways. The wires looked ok and I couldn't find any noticable defects with the coil pack but who knows I did notice cylinder 2 and 3 are on the same side of the pack. I think i'm going to have the CAT replaced and go from there (The CAT is making all kinds of noises). If that doesn't fix it I may take it to the shop and have them look at it.


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## rabbott73 (May 20, 2010)

Again the error codes i'm getting are:

PO302 - cylinder 2 misfire
PO303 - cylinder 3 misfire
PO422 - something to do with the CAT threshold out of wack


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## Robert Roberts (Jan 30, 2009)

mist the wires and coilpack with a water bottle. 

While car is running, listen for changes in the sound of the engine (misfires etc..) and look for the mini lightning light show (arcing). If you notice either, you need to replace whichever part you sprayed (noise while spraying wires = new wires, likewise the coilpack) this test is easier to see (and more fun) at dusk or in a dim garage.


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## phatveedub (Sep 28, 2001)

Hey, i was wondering if you ever had a resolution to your daughter's car problems earlier this year. i have the same codes and symptoms that you had and i am at a loss. i was thinking it was my cat too but would like to know what you did before i spend the 300 bucks for a cat.

Thanks
Ed
[email protected]


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