My CEL is on and the code is P0420. Now we ran the OBD2 when the car was running and both O2 sensors seems to be working fine. There is also a squeal on start up and upon acceleration which we do not know if that is linked to the Cat Conv. code. Any thoughts or ideas, has anyone had this code come up and it was a repair that was not directly the Cat Conv? Thanks in advance.

 

I have been reading a lot about vacuum leaks causing the air to be enriched which throws off the sensors. since I think I have a vacuum leak I want to track this down but have had a lot of trouble finding it. Anyone know of common air leaks on these volvos?

 

Generally if you have a vacuum leak it will throw the P0101 code for the Mass Air Flow sensor.
Is your car a turbo or N/A? There's been cracked plastic pipes that are part of the PCV system, old and cracked vacuum lines. Leaks really could be anywhere. Do you have access to a smoke tester? It will pressurize the intake system with smoke so you'd be able to see where the leaks are coming from. If it's a large leak, you'll be able to hear it.

Even though the O2 looked good while connected to the OBDII, it still may actually be a bad sensor. I'd start with the leak test since it's the cheapest option, then I'd look into replacing the rear O2 sensor then go from there.

 

Ok thank you, and no mine is not a turbo.

 

Could the oil trap/PCV system be malfunctioning. I read where a lot of people were having a whistling sound and the CEL came on. I also hear a high whining sound coming from my engine bay after driving for a while. I am trying to solve this by looking at every angle before jumping in and throwing all new parts in that may not be bad. Thanks.

 

This is all I can see under my intake manifold. This is the oil separator tank, is this the same as the "oil trap"?

 

Yes, that's the oil trap.

Please try to keep your problems seperate. The car is getting older and many problems may exist.

For the P0420, you may want to try this:

As for the squeeling noise, try to disconnect your serpentine belt and see if the noise goes away. If not, it may be a timing belt roller/idler/tensioner which is real bad news. You'll want to get that taken care of sooner than later. When was the last belt change? Did they also change the rollers?

 

I was thinking that the oil trap was causing the squeal and as I mentioned people were getting CEL when it happened. I wasn't sure if this was the case for mine so I'm trying all this to solve the cat problem, not just randomly posting problems all under one thread. Sorry for the confusion. I may try the lacquer thinner which seems sketchy but it might work. Thanks for the video.

 

Hello

I have 2002 s60 volvo, the check engine light came on, i run test and P0420 came as code, i cleared it check and found exhaust leaking under the car, i have it repaired and the problem has not come until now.can exhaust leak far after the o2 sensors triger the check engine light.
Thanks

 

I'm not sure but it usually takes about 400 miles for the code to return once reset. The system has to post READY before it will report that code.

BTW, I did try the lacquer thinner trick and had no problem with it.

 

I unhooked both positive and negative battery cables over night, the next day the car was driven just over 50 miles when the light came on. A reputable Volvo mechanic said that he sees this light all the time but it has never been the cat

 

Reviving an old thread but I am heaving this issue right now, was there a resolution to this problem for you?
P0420 Catalyst System below Efficiency Threshold Bank1

 

Delirious, I too have the problem. So far, I have replaced the rear O2 sensor but the problem persists. The waveform reading (read on my OBD2 reader) of the rear sensor shows it varying between .09 and .9, which usually indicates a bad cat. Not surprising for me, as the engine has 280000 miles on it (on a V70 2.4 NA). My next step is to try cleaning the cat by running 1 gal of lacquer thinner thru the engine, and putting a spacer in line with the O2 sensor. I will check back once I have some results. Last thing I wish to do is replace the cat $$$.

 

I an getting P0420 and 2nd code P0420 p/d does anyone know if this a cat problem or o2 sensor or both...not cheap[????