Driving to work this morning and it threw a CEL. I went straight to AutoZone to get it checked. They pulled the P0420 code. The description is:

The PCM has determined that the catalyst system efficiency for Bank 1 is below threshold for the current engine operating conditions. (Bank 1 identifies the location of cylinder #1, while Bank 2 identifies the cylinders on the opposite Bank)

They said it was the catalytic converter, but I wanted to check if it could be something else (such as a sensor or something). I also wanted to know how serious this is. From what I know, it's not that big of a deal unless I need to get the emissions checked.

I have an '00 with 84K miles and the stock exhaust.

I'll prob just pull the fuse to reset the computer and see if it comes back on, but any feedback is appreciated!

 

Reset the ECU and forget about it if you don't get another

 

DTC P0420: Catalytic System Efficiency Below Threshold.

1. Reset ECM
2. Start engine. Hold the engine at 3000 rpm with no load (in neutral) until the rad fan comes on. (this may trigger an EPS light, which will have to be reset later).
3. Test-drive 40-55 mph for 2 minutes. Then decelerate for at least 3 seconds with throttle completely closed. Then reduce the vehicle speed to 35 mph, and try to hold it until the scan tool indicates FAIL or PASS.

If FAIL, check the cat, replace if necessary.
If NO fail, system is OK at this time.

(I guess without a scan tool, you'll get another CEL eventually.)

 

Thanks guys.

I don't have the scan tool, but I'll try that and see if the cel comes back on.

 

This is seems to a reoccurring issue with S's regardless of MY when the mileage is about that high..

For the other cars I know of....it was the CAT.

 

I didn't even notice the miles

EDIT: This is unrelated to your CEL but, if you haven't done so already, go get a valve adjustment.

 

Adjusting the valves isn't going to fix the problem. The convertor is faulty, and the only fix will be to install a new one, or go for the illegal test pipe. Most likely the first monilith block has broken loose from the outer casing, and will be smashing into the rear 02 sensor.

Check your local emmisions laws on what is required/penalties for having a test pipe.

You could always pick up a low miles used convertor in the FS forum, lots of people removing them for a test pipe. You will need a some type of simulator for the 02 sensor.

 

Sorry, the valve adjustment suggestion was supposed to be unrelated to the issue.

 

I did some searching and of course this is covered by the 80K warranty and I'm at 84K I haven't had the chance yet, but I'm going to reset the ECU and then see if it comes back again. If so, I'll be back possibly with some more questions about a test pipe.

Jasonoff, thanks for the pointer on the valve adjustment. I've been meaning to get one, but haven't had the chance. Hopefully I'll get it done soon.

Thanks for lookin out guys!

 

i had this problem a few weeks ago.

same CEL. its the cat, im sorry, but thats what it is. if you had this code along with others it could be the sensors.

luckly for me the deal covers 8yrs/80000miles on cats. so i got a free one..

good luck.