I figured I'd run this by you guys.

2001 VW Golf GLS. Throwing a P0420. Catalyst Below Threshold Bank One.

I've read a bunch of stuff and come up with this.
It could be a cat. Could be a sensor. No one seems to know.

The car has been acting funny for a LONG TIME... go figure. The temp gauge will drop to full cold when the cars been running for a while or sometimes won't even come up. Never goes over 190. I don't get it.

I'm wondering if it's a MAF sensor issue, a toasted Cat or a bum temp sensor somewhere.

I don't have money to be throwing at this car so I don't want to wonder around guessing. I cleared the code. It hasn't come back yet. The MAF sensor was replaced last year. The thermostat about a year ago. Etc.

Stupid VW.

 

The cats on those things suck. Double check that it isn't still covered. The warranties were extended on them for a reason.

 

It's got 148,000 miles on it and we bought it used at Bob Lewis VW. How can I check?

They haven't honored a single warranty issue we've brought it in for. Worse dealership in the history of man kind.... worse than yours even. lol...

Too bad I missed out on the driver gig. Let me know if something comes up. haaa.

 

Nevermind. You're out by mileage. Federal was extended to 8/80k.

The temp sensors on those go bad as well. I'd start there. I was having an issue with my ex's Jetta that sounds similar. Temp sensor and cat were to blame. Temp sensor is a five minute and ~$40 fix.

 

I think I'll give that a shot first. If it's just a cat I don't care. haaa. It just passed smog with flying colors.

That's why I thought it might be the temp sensor. Now to find directions on where to find it and what to buy. Damn VW's nothing is easy.

Hell it took me a couple minutes just to find the OB plug in for the reader. haaa.

 

Ray, as far as the temperature issue, it's the green temp sensor on the coolant outlet on the head that's gone bad. Easy fix. The CEL, however, is probably the O2 sensor. If you can drive up to Palo Alto, see Darren at Streetwerke. Really good guy, and he'll check it out with VW/Audi diagnosis systems ( VAG-COM ) for free.

 

Damned sensors.

I'll try to get out there. If I do I'll drop you a line.

When my cat went it gave me a CEL. I cleared it. It never came back. I guess subaru's are smart enough to go... well if he doesn't care why should I... haaa.

 

Ray,

http://www.blauparts.com/proddetail.asp?prod=GD31020

Good luck. Like I said, I went through the exact same thing.

 

Dude... the part is $24.95... they have a $25 minimum purchase. Friggin lame.

 

Ordered part. Thanks. I also ordered a box of nitrile gloves. $14 for a box of 100 isn't too bad a price and I had to get the order over $25. haaa.

 

That's not super cheap, but not awful. I think I paid about the same price for the part at a local VW dealer. Either way, let us know how it goes.

 

Will do. Yeah I thought about going to the local dealer but the one here in Gilroy is a rip off. Charged my wife like $150 to change a head light bulb. And they're idiots.

 

My suby had the same code, CAT and both O2 sensors replaced, still have the code. Also know a Jetta owner that went through the same thing, VW replaced CAT, O2 sensors, still got the CEL code. Be prepared for it to stay.

From what I read, if the O2 sensors don't fix it, it's MOST LIKELY an exhaust leak. Somewhere I read the Subaru Service procedure on a P0420 and the first thing to check is for exhaust leaks on the header/exhaust manifold. If no leaks, then replace O2 sensors.

Another theory of mine is the ECU's on the VW and Subaru's have too strict of tolerance for what the O2 readings should be, so it is throwin the code at the smallest discrepency.

 

Yeah. As long as things are running good I'll just keep clearing it.

But the temp warning on the dash keeps going off for no reason. Like right when the car starts and stuff like that. So hopefully my temp sensor will fix both issues. Car just needs to hold together for another year or so. Both our cars are at 150k so we have to do something soon.

 

son of a biscuit. I am so stupid.

I picked up the wife's vw book and read about all the warnings. Apparently if the coolant gets low the temp warning light goes off the same as if it was getting hot. I added some coolant and the things stopped flashing.... So I figured I might as well change out the sensor since I bought it. Took about 3 minutes.

So far the temp warning light is staying out and the temp gauge seems to be working fine. No to replace the fuel filter.