1999 beetle P0422 which O2 is bad the o2 before the cat or after

code p 0422 refers to main cat converter, bank 1 ---efficiency below thresh hold ===causes cat converter,--- wiring -- heated oxygen sensor (HO2S) 2
heated oxygen sensors are the ones in the exhaust manifolds before the cat converters
they are wired and the wires are delicate and can be easily damaged
O2 sensors (O2s) are found after the cat converters and can determine the quality of the cat performance
At this point I would be looking at the HO2S replacement as that is what the code indicates --IF-- the cat is in proper working condition

Possible causes
- Warm Up Three Way Catalytic converter deterioration or malfunction
- Exhaust system leaks
- Loose front or rear HO2Ss
- Faulty front heater O2 sensor
- O2 sensors harness is open or shorted
- O2 sensors poor electrical connection
Tech notes
As the code description implies the P0422 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0422 code is combined with other codes, try fixing the other codes first.

MUFFLER MIGHT BE PLUGED

exhaust doesnt sound like a code, there should be more to code than cat or exhaust, the cat code is probably like cta efficencey below thrushold. this means the converter is not working, the cause maybe bad cat or bad oxygen sensors, testing may be needed to see if o2 sensors are working good. the exhaust code i dont know, never heard of exhaust code, they may be caused by the same problem, start with the cat code, have o2 sensors (oyxgen sensor) checked or if over 100,000 miles replace them. if converter is bad it a very good thing to also replace the o2 sensors with the new cat.

you can do that since you already replace the cat, however the problem may be some where else like maf sensor, intake leaks faulty plugs, coils or fuel injectors

P0422 - Catalyst below threshold.

Catalytic converter is clogged or out of medium.

Replace it.


ACTUAL DIAGNOSTIC:

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.

Symptoms

* 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



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P0422 is a code for catalytic converter efficiency. It shows up if both upstream and downstream O2 sensor read exactly the same indicating the converter isn't working. The only way to get rid of the code and keep it away is to replace the converter. That doesn't mean you need to spend 500 dollars on a factory one. You can buy a universal one and have it welded in if you buy a good quality one. Usually aftermarket ones run about 120-180 dollars

O2 sensor replacement is a good thing to do right away. After this disconnect the positive lead to the battery, wait about 30 seconds and reconnect. This should clear the error codes. Now go somewhere where you can floor it and go through the gears a couple times. This will establish a new acceration curve. If it's a real problem the lights will come back on, if not your good to go.

P0422 does not refer directly to an O2 sensor. That is a different code. P0422 is about the CAT. How many miles you have it and when did you buy it? VW has extended a warranty on the New Beetles for the CAT to 120,000 mi and 10 yrs. I had the same code and took it to the dealer to see if they'd replace the CAT in the warranty and they did. I had 47,000 miles and bought it at the end of Aug 1999, so I just slipped through. They replaced the downstream O2 sensor as well - all free of charge!

P0133 is an oxygen sensor "response too slow" code (meaning it's not getting up to temperature quickly enough, and the computer is assuming damage to its heating element). P0422 is a catalytic converter problem indication (cat is below peak efficiency). It's assuming you have a failure with the primary O2 sensor and that the cat is also bad. Change your O2 sensor first, have the codes cleared, and see if the cat code comes back or if the O2 sensor change fixes both issues.