Do You Think My Catalytic Converter Is Clogged Up?

[Rigger Jim]

I have a 1995 S14 240SX. I recently took it to a dealership and had them change out my EGR Solenoid and clean out the EGR hoses. On the way home my check engine light came on. So I hooked up me diagnostic tool, and it said that my EGR System wasn't functioning correctly. So, I took my car back to the dealership and had them clean out the hoses again. On my way home the second time, the light came on again. This time it gave me the code: P0420. Under the code it said, "Catalyst System Efficiency Below Threshold." So my theory is that when the dealer cleaned out my EGR hoses, they blew some stuff into the Catalytic Converter and clogged it up. I was wondering if anyone else had recieved this code and what they did to resolve this problem. If it is the Catalytic Converter, I'll probably just switch it out with a test pipe. Is it difficult to switch out the Converter on an S14? All help would be greatly appreciated.

[alfsnissan]

Does the car do anything out of the normal? Or are you just getting the code? It’s not hard to change, you have 3 bolts holding it to the exhaust manifold. You'll have to cut the pipe after the cat tho. I changed my cat and wanted a new stock one. They where close to $900, so I went to a local custom muffler place and they had a cat that almost matched the angle of stock. Cat and labor only cost me $120.

[Rigger Jim]

Well it has started smelling like smoke inside the car. Other than that, there are no problems. And this is the only code the check engine light gives me.

[1KleenS13]

PO420 is the most common emission code thrown. Alot of times the cat is still good but the o2 sensors get lazy. Does this car have a post cat o2 sensor? I would place my bet on the rear o2 sensor. But the cat could also be shot if the car was dumping fuel into it. If your cat is clogged it wont run very strong, and if you pull out the front o2 sensor it sould run better.

[Rigger Jim]

My Chilton Manual only mentions a front O2 Sensor. My sensor went bad awhile back and I had it replaced. Maybe this could give me trouble? But if there is a problem with the O2 sensor, wouldn't the ECU tell me?

[Rigger Jim]

So there are new scary developments. On my way home from school today, all hell broke loose. I started hearing a rattle from under the car. So, I figured at check it when I got home. (it's a 10 min. drive) A few minutes later, I started smelling a stronger smell of smoke. Then white smoke started coming from the exhaust. At a momentary stop in my trip, the smoke started going past the driver side window. SO, I pulled over and popped the hood. The AC hoses were covered in fresh oil. And, white smoke continued to spew out the exhaust. Then, I started hearing a high pitch spraying noise coming from the rear of the vehicle. As I depressed the gas pedal, the spewing noise got louder. It was kind of like a jet taking off. Anyway back to the engine. There a bunch of visibly loose bolts that the dealer had failed to tighten. These were all intake parts. They had to disassemble the intake to get to EGR. So, I guess I need take it back for a third time and make them fix it for free. I think they left something loose again. I hate those lazy jerks.

[Rigger Jim]

Oh yeah, I find this pretty funny. The check engine light went off!!!!!!! When the car finally decided to fail, the check engine light went off.

[1KleenS13]

Looks like the dealer is going to be giving you a new motor. Dont take no for an answer, if they screwed up its on them to fix it.

[OutToWinPAHC]

Is the header turning bright red and temps climbing? Walker replacement cats aren't bad.

[Rigger Jim]

I got my car back from the dealer yesterday. The temperature is normal. It's pretty much always in the middle. Anyway, the dealer told me that my valves are leaking oil at the stems. They suggested that I rebuild my engine and get new timing chains and guides. But my question is: Why did all this crap go so wrong while the dealer had my car? They were supposed to just be cleaning out my EGR hoses. The service administrator said that if I couldn't afford to rebuild my engine, I should mix Stop Smoke into the oil. So, I guess I'm just going to have to mix in the Stop Smoke until I can save up some more money. This sucks.

[OutToWinPAHC]

NO!!!! Oil additives are bad, they do more harm then good. There is a write up on valve stem seals, Timing chains and guides. Its not that hard and would cost a total under 300 if the bottom end is good.

[Rigger Jim]

Thanks for the advice. A week ago, I put in 1 quart of Hy-Per Lube Smoke Stop when I changed my oil. Since then, I haven't seen a single puff of smoke. And, the engine seems to run better. I think I'm just going to do an engine swap for a lower mileage engine. My car currently has the stock KA24DE with 197,000 miles on it. I might put in a Skyline engine while I'm at it.