What does this engine light code mean?

badgett · Post by **badgett** » Wed Jun 04, 2008 10:59 am

I can't remember the p number but my code reader says this... (catylist efficency below threshold, bank one) Is that my cat converter or an O2 sensor?

01neon01 · Post by **01neon01** » Wed Jun 04, 2008 11:53 am

try checking your codes by turning the key to the on position, buy not turning the car on, then off. on-off-on-off-on-off, then the cod should come out. you might end up needing to get a cat

Donkeypuncher · Post by **Donkeypuncher** » Wed Jun 04, 2008 12:01 pm

It could be just 1 or both. Usually it's the O2 sensor, but there have been a few members with bad cats lately. Does the cat glow after a long hard drive?

Post by **occasional demons** » Wed Jun 04, 2008 12:21 pm

I think that's the code that pops up with no cat. The upstream and downstream o2's readings are too close to being the same. Possibly the honeycomb has already blown out the tailpipe. Every now and then they disinegrate just enough to be blown out the tail pipe, or collect in the muffler.

01NeonSnooZer · Post by **01NeonSnooZer** » Wed Jun 04, 2008 1:11 pm

Simple test. Take a rubber mallet or rubber faced dead-blow hammer and tap the cat. If you hear a bunch of rattling around inside the cat, ya need a new one.

Now this test isn't gonna cover the possibilty that the catalyst may have disintegrated and blown out the tail pipe but its a good start and something you can do in your driveway/ apartment parking lot.

badgett · Post by **badgett** » Wed Jun 04, 2008 1:34 pm

My car has started struggling on hills lately. My wife has also told me she has seen a cloud of grey smoke when I leave in the mornings. Not blue smoke or black but a light grey. I will try to look at it at night after a long drive to see if it glows. I just don't want to buy an O2 sensor or a cat until I figure out which one it is.

aperson · Post by **aperson** » Wed Jun 04, 2008 2:10 pm

Sounds like cat, but I would replace the O2 sensors first. Normally they will fix the issue. And if not, it's probably time to replace them anyways. The grey smoke could also be the engine running rich on the default fuel map also.

01NeonSnooZer · Post by **01NeonSnooZer** » Wed Jun 04, 2008 5:55 pm

if it glows, let us know because there has to be a reason for it to glow. If it's glowing, your car is probably running rich and so it's causing your cat to glow. Youd have to figure out why it's running rich (O2S, False Air, bad MAP value, etc.).

ewetho · Post by **ewetho** » Wed Jun 04, 2008 10:36 pm

If you had access to a scan tool you would check the 02 and see how they switched. If the down stream just went flat and stayed either lean or rich and never switched (remember it only does this switch like every 10 seconds or longer) could be a sensor. If it starts to follow the primary sensor at the same rate then you have a bad cat.

At my work when the cat goes bad, whe replace the secondary sensor too.

Post by **occasional demons** » Thu Jun 05, 2008 7:31 am

ewetho wrote:. At my work when the cat goes bad, whe replace the secondary sensor too.

DCX generally recommends replacing them in pairs. Their claim is that one can influence the other through the ground circuit.
but in this case if the cat has failed, I would think it's more of a overheat/contamination issue.

01NeonSnooZer · Post by **01NeonSnooZer** » Thu Jun 05, 2008 10:04 pm

ewetho wrote:If you had access to a scan tool you would check the 02 and see how they switched. If the down stream just went flat and stayed either lean or rich and never switched (remember it only does this switch like every 10 seconds or longer) could be a sensor. If it starts to follow the primary sensor at the same rate then you have a bad cat.

At my work when the cat goes bad, whe replace the secondary sensor too.

The downstream sensor isn't supposed to be switching very often at all because it's in the axhaust stream after the catalyzation has already taken place. The upstream sensor should be switching rich to lean and back pretty quickly because the 3 way catalysts are finnicky. The catalyst is divided into 2 parts and the 2 parts work differently, one part converting the CO (carbon monoxide created during the righ portion of the switching) into environmetally harmless Co2 (plants use carbon dioxide for photosynthesis), and the other portion stripping NOx (Oxides of Nitrogen, Not Nitrous Oxide) of some of it's oxygen molecules and sending them to the other portion of the catalyst for the conversion.

On topic, though. If the cat is glowing, there's too much unburned fuel in the exhaust so more than likely, if the O2S is damaged, it would probbably be more due to carbon buildup on the sensor. But something else has to be wrong/inop to cause the rich condition which has damaged either the cat or the O2S. You'd need to scan it to see if the upstream sensor is switching. If not, it'll either be reading constantly rich, or constantly lean. Now if the catalyst has simply broken loose and disintgrated (not melted by overfueling), then you have no catalyzation taking place and both the upstream and downstream O2 sensors will be switching at the same rate with a slight delay between the two due to the space between them.