Question about 1999 Volkswagen Jetta

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1999 vw jetta 2.0

Check engine light is on and codes
po422 main caytalyst efficienty below threashold bank one
pending codes
po300 ramdom mult. cylinder 1 misfire
po134 oxygen sensor bank one no activity
po303 cylinder 3 misfire

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  • 6 more comments 
  • foozi4 Feb 03, 2009

    99 jetta check engine light comes on 70 miles after resetting. Code po 422 come up .I changed forward o2 sensor and its no different.Any suggestions?

  • uwantme2g Feb 08, 2009

    my check engine light wont shut off and i cant find where the plug for a computer is at under the steering wheel

  • pescatello m Feb 27, 2009

    I have a 1998 Jetta. We have been able to clear all codes except 422. Any suggestions?
    Also.... Plug for computer is under cig lighter, not under dash.

  • Anonymous Mar 12, 2014

    check engine light says 8th cylinder is misfiring

  • Anonymous Mar 15, 2014

    multiple misfires codes po300 p0302 and po303

  • Anonymous Mar 16, 2014 has misfire #7 cylinder location of bank 2 sensor 1 olso need firing order

  • Anonymous Mar 16, 2014

    also bank 2 sensor 1 codes

  • Anonymous Mar 25, 2014

    i need to know where is located



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Sounds like two problems. P0300 and P0303 are possibly spark plugs. They could be a coil pack but I'm leaning toward a spark plug problem because of the other two codes - they're indicating O2 sensor problems. If the O2 sensors are screwed up, the car reverts to preprogrammed, rich fuel maps that send excessive fuel through the engine. The reasoning is, if the ECU can't trust the O2 sensors to determine how much fuel to burn optimally, it'll pump a bunch of extra fuel through the engine to keep it safe. Having too little fuel (aka running lean) can destroy an engine, so the ECU plays it safe and runs rich (too much fuel) instead. The consequences of rich running are relatively minor compared to lean running, but can and do tend to create excessive carbon buildup on the catalytic converter and O2 sensors, as well as fouling spark plugs.

First thing to do though is to swap the wires on your coil packs and see if you end up with a misfire code for the same cylinder #3. If you do, then it's the plug or wire. If it moves, it's the coilpack. Replace whichever part is faulty. You'll probably need oxygen sensors too, before you can clear all the codes.

Posted on Sep 02, 2008


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Getting a PO422 code on my 1999 hyundai elantra the code says main catalyst sufficiency below threshold on bank # 1 and the check engine light is on.

i think it means that the catalyst converter needs either cleaning or replacing because it's not working properly because it's either blocked up or damaged. not sure which side is bank one though. the check engine light may come on for many reasons. first of all check oil level and condition of oil if it's alright the easiest thing to do is check the book that came with the car and see exactly what reasons the engine light comes on for.

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Hello i have a GTI its a 2.0L manual transmission, i have been having problem after problem thus far. Current engine codes PO422, PO300,PO304,PO303,PO302. I do not have a code list to see what these are...

I think that PO422 is the Cat Converter, it may be bad or may be just the O2 sensor.
The PO300, 302, 303, 304 code have to do with the ignition coils or wires. (302, 303, 304 means there are ignition /firing problems in cylinders 2, 3and 4). If your lucky just the wire and new spark plugs.
Google "engine codes Jetta" for more on web. Good luck.

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I have a 2000 vw jetta vr6 gls 2.8 and it sounds like it is misfiring but the check engine lights is not on. When I accelerate it sounds like im driving a lawn mower. What could it be?

The check eng light does not always come on when theres an issue. Take it and have it scanned anyway, I bet there is a code stored, Also ask them to check Pending codes. Pending codes are what the computer has noticed a possible concern and is watching That system, Pending codes can be saviours when diagnosing a hard to find issue

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The check engine lamp on my vw jetta 3 is ''on'', i put a diagnostic reader on and it showed the following codes:P0422,P0411,P0300B,P0301B,P0302 and P00172B, what do they mean and how can i solve the...

P0422 - Catalyst below threshold.

Catalytic converter is clogged or out of medium.

Replace it.


Fault Code Definition
Code P0422 indicates that the Bank 1 Main Catalytic Converter's emissions efficiency has fallen below the minimum allowable limit. This threshold is tracked by a Catalyst Monitoring Oxygen Sensor located on or near the outlet of the Catalytic Converter.


* Check Engine Light will illuminate
* In many cases, no abnormal symptoms may be noticed

Common Problems That Trigger the P0422 Code

* Defective Catalytic Converter
* Engine misfires have damaged the Catalytic Converter
* Internal engine damage resulting in high oil consumption and/or a leaking Head gasket has damaged the Catalytic Converter

Common Misdiagnoses

* Oxygen Sensors are replaced when the real problem is a damaged Catalyst
* Catalyst is replaced when the real problem is internal engine damage, which is producing elevated emissions levels
* Catalyst is replaced when a misfiring engine is the real problem

Thanks for using FixYa - a 4 THUMBS rating is appreciated for answering your FREE question.!@#$%

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1 Answer

Obd codes po131 sensor circut low voltage,bank 1,sensor 1. And po422 main catalst efficiency below threshold,bank 1 came up.I wanta know how to check and fix this.

If the 02 sensor has over 70,000 on it then replace it.

If the spark plugs have over 60,000 replace them.

Make sure you have no vacuum leaks and no exhaust leaks.

If the timing belt is past its time which is 60,000 miles, replace it.

If all this checks out and you still have the cat code then the catalytic converter will need to be replaced.

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Check engine light is on

The cam shaft sensor is faulty. replace this sensor. the light will go off when this replacement is accomplished.

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Wondering what the error code we were told means

First, the check engine light just means you are not meeting emissions right now. Not a big deal. Try disconnecting the battery for 1/2 hour and then reconnect and drive car for 10 miles. It may run rough while it relearns you engine controls again but it often clears the codes.

Now, codes are only 5 digits so I assume the 2 is extra.
P0420 = catalyst efficiency below threshold (bank 1)
P0240 = can't find this code.

Autozone also does free scans. please rate for me, thanks

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time for a tune up. plugs and wires.

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I have two check engine lights on P0303 and P0422

A good start would be to go you the Diagnostic Trouble Codes list at

The DTC's, also known as fault codes, may have other meanings but the list above should point you in the right direction.

Hope this helps - if so a rating would be really appreciated. If is doesn't then "add a comment" instead and I will try to help you further.
Cheers D..

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