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1999 GLS 2.0 m/t
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189 Posts
Discussion Starter · #1 ·
I have a 1999 NB w/ 2.0. I've had it about 3 weeks now. Since day 1 the check engine light has been on. So I ordered a V-Checker Pro Scanner. Today it arrived and I checked the codes. Only one was present 16806/P0422. Iooked it up and found this...

16806/P0422/001058 - Main Catalyst: Bank 1: Efficiency Below Threshold
Possible Causes
• Oxygen Sensor(s) defective
• Oxygen Sensor(s) Control defective
• Catalyst faulty
Possible Solutions
• Check Oxygen Sensor(s)
• Check Oxygen Sensor(s) Control
• Perform Oxygen Sensor(s) Aging Check
• Set Readiness

:confused: My question is, how do I figure out which o2 is bad?:confused:
 

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The P0422 code means that the ECU has detected a condition that could be caused by a failing catalytic converter. It uses the signals from the two Oxygen sensors to determine this. The first thing to do is use the scan tool to check the function of the O2 sensors. If those check out then chances are (given that you have no other codes present) either the catalytic converter is bad or there is an exhaust leak in the section between the two O2 sensors. The original catalytic converters were not too durable in the early New Beetles, so if yours has been replaced with a weld-in replacement check the welds for leaks. Here is a video that describes how to use the scan tool to check the O2 sensors and how to check a catalytic converter.

https://www.youtube.com/watch?v=9VZ5K8n5jj0
 

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1999 GLS 2.0 m/t
Joined
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189 Posts
Discussion Starter · #3 ·
red99 thank you for the reply and info. I'll try to check after work tomorrow when it's warmed up good.
 
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