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Discussion Starter #1
I did a coil conversion on my 02 1.8t passat since then I been throwing a code p0420. I am using the PFR6Q plugs gapped to .40. I don't know if I should of left it at its stock gap at. 34 or not. Car is not chipped. Car runs fine otherwise.
 

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Discussion Starter #7
I did the same a few months ago. Stock car stock gap.
that's what I figured. I went back to the stock gap. Since December I did this coil mod my car has given me the p0420 engine light. I am hoping it goes away. Next time it comes on I am going to have my guy look at it.
 

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I have a hard time seeing the connection between P0420 and plugs if there are no other problems, but your gap is too big anyway so I would reduce it first.
 

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Discussion Starter #9
I have a hard time seeing the connection between P0420 and plugs if there are no other problems, but your gap is too big anyway so I would reduce it first.
I don't know. Soon as I did this I started throwing a p0420 a month later. I put the gap back to 0.034 stock. Should I go lower?
 

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Stock plug gap 0.032" (0.8 mm)


16804/P0420/001056 - Catalyst System; Bank 1: Efficiency Below Threshold

Possible Causes
Leakage in Intake and/or Exhaust System
Catalyst faulty
Oxygen Sensor(s) faulty
Oxygen Sensor(s) Control faulty

Possible Solutions
Check Intake and Exhaust System for Leaks
Check Catalyst
Check Oxygen Sensor(s)
Check Oxygen Sensor(s) Control
Perform Oxygen Sensor(s) Aging Check

Special Notes
For 1.8T's experiencing this fault code, this thread may be useful: VWVortex.com - Aftermarket DP/Cat -DTC - Cat efficiency below threshold - Who has this DTC and wich DP/Cat
Check the Official Factory Repair Information for any TPI/TSBs that apply to dealer level Engine Controller flash updates for the vehicle in question.
 

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Discussion Starter #11
Oh crap 0.032 not. 034 Read wrong again I'll gap them tonight. I had a mega leak on my flex joint and some coupler. They were repaired could be just a fluke it came on during the leak and after I just had it fixed. Maybe that caused it?
 

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Discussion Starter #13
I will be driving my car Friday. I had some suspension work done and I need to get it aligned before I can drive it 30 miles. I did notice my milage was not great. I'll see if it's better with it gapped somewhat better. I had a old post about gap questions when I was getting rdy to do this and I must of misread the post while I was at work to gap them at 0.040 oops haha
 

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Gapped to .040 is too much gap. Even .032 is just outside of the OEM specs of .8mm (which is .031XXXXXX converted). The NGK's are factory-gapped at .032, btw. I would NOT, however, just blindly installing them without checking the gap to verify. NGK has a nice section on installation info at their website.
 

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Discussion Starter #15
I'll check it out after I finish the control rods. This car is getting more attention than my wife lol
 
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