My 04 Durango keeps throwing "Catalyst Below Threshold" code. Cat convertor is still in decent shape, wondering how to clean off th sensors to see if that helps. Any help would be appreciated. Thanks.

 

What is/are the exact code(s) it is giving you?

 

it is giving a P0240. That is the only one that shows up.

 

I apologize, the code it is throwing is P0420. Got the numbers confused when I wrote them.

 

http://www.obd-codes.com/p0420

This may help,
FF

 

Hick:

How many miles on your D?

Sounds like the cat is not doing its job, or the sensor is bad.
It would be one of the two downstream O2's assuming you have dual converters.

If your rig is under 80K, a converter replacement would be free at the dealer. I think I would consider replacing the suspect O2 first as a way to rule that out.

You also might try a battery disconnect to see if the CE light returns, or was just an abberation from a bad tank of gas etc.

Don

 

95k on the D. Went to replace bank 1 sensors, and they are 75 ea, bank 2 are 32 ea for Bosch. Opted for just cleaning them first to see if that would do the trick. So far so good.

 

Cheaper place to order the sensors from:

www.rockauto.com

The Denso ones are less then $40, if memory serves. Denso are the factory OEM units, without the high markup from the $tealership.

 

I have a somewhat similar problem with my 90K mile 2006 Durango 5.7 - after starting (generally cold), about 1/3 of the time the car will run very rough and idle slow for about 15-30 seconds, and then will be completely fine. When it does that, it throws a "Random Misfire" OBD code which I don't seem to have written down. It will ALWAYS throw the P0420 code, and occasionally throw P0004, which apparently is a transmission code than inexplicably says "Fuel volume regulator control circuit high."

The local dealer has looked at it and has no idea, but recommends replacing the CAT on that side for $800. It doesn't make sense and is an expensive way to start and I haven't been back. I thought I'd try replacing the downstream sensors and the actual sensor seems pretty easy to get to but... (see question 1).

QUESTION 1 is how do you unplug and replug the sensor wire, which seems tucked way up in there?
QUESTION 2: does anybody on the board know of a quality service shop in the Rockville/Bethesda/Gaithersburg MD area?
QUESTION 3: It seems like detective work, but this happens about a third of the time, and ONLY after 30 seconds of running, and never lasting more than 30 seconds. Anybody think of a possible cause rather than just randomly replacing parts?

Thanks in advance.
Peter