Mercedes Benz 1989 300E Catalytic Converter Help.
 

I just bought this car and it happened to fail Ontario's Emission test. It's a Mercedes Benz 300E 4dr 1989.

The people at the garage said I need to replace my catalytic converter and I also need to buy a new O2 sensor. They can't go on with the diagnosis as to why my car failed the E-test without those parts. The problem is, they want to charge me $1100 CDN for the parts, and $250 CDN for the labour.:eek::confused:

I have seen catalytic converters for 50% - 80% cheaper than the mechanic's price. So my question is, do I need a Mercedes Benz 300E specific cat/con, or could I just buy one of those universal ones and get my mechanic at work to hook it up for me? I don't mind getting a Bosch O2 sensor.

Please help me. I appreciate any help offered.

Thanks a lot.:)

Hi
I would diagnose the problem first. After I failed a test, the guy who tested also kindly offered to replace the catalytic converter - that is easy money for these guys. In the end, I diagnosed a faulty EGR valve. I do not understand why they need to replace the catalytic converter to go on with diagnosis? How did the car fail, can you provide the values from the test?
Bruno

It's an Ontatio E test

I know it failed CO2 emission. The limit is 1... and my car got a whopping 4.28.

They basically said my exhaust is bad and I gotta fix it for them to continue diagnostics. As well as replacing the oxygen sensor.

I really don't mind replacing the Cat/con, I just want to know if I can use a universal one instead of the $700 Mercedes Benz ones.

You probably mean CO? It could be due to bad mixture adjustment. I see no reason why you could not use a generic cat. Obviously, it may need more work to make it fit, but functionally it should be fine.
Bruno

Alright, thanks a lot. Extra help is welcome guys.

If your CO is 4.28 %, you're running way too rich.
This could well be the sign of a defective oxygen sensor.
May be worth while replacing it, as you're also waisting a ton of fuel.
I installed an aftermarket catalytic converter on my truck about 8 years ago, and it passes the Ontario Drive-Clean Test, every two years, with flying colors. ;)
Mine is made by " Walker " Exhaust.
Check with any good mufflershop.

Would changing the spark plugs, oil, muffler, and filters also help with the E test?

There are better experts on emissions than me but here is my opinion:

The O2 sensor and the cat do 2 different things, so to say you need both is a little fishy IMHO if you just have the one problem. As was just said, the O2 sensor might well solve your problem. It is cheap and you can DIY. I had the same problem with my Toyota, high CO, really high like yours. I changed the cat, NO IMPROVEMENT. I change the O2 sensor, CO went to 0. I would put in the O2 sensor and get it tested again.

Mike

A lot of people at auto parts store will say things like this. I think that is why they work at auto parts stores. You could make an argument for the air filter, but essentially the answer is no.

Mike

start with o2 sensor, sounds like it went short to ground feeding the f.i. computer a 0.00 signal which commands it to keep richening as far as it can.

There was another part of the test. I don't know what it's called. But basically, the limit was 200, and my car scored 237. Anyone know what it might have been?

Hydrocarbons. Exact same as I had. For the love of GOD please change the O2 sensor. We could be wrong but I don't think so.

Thank you

So the O2 sensor is the top priority

Then the Catalytic converter

After that oil change + air filters.

I'll get to that ASAP. Thanks for helping guys.

Did your car not have an emissions test, ( as well as a safety check ), when you purchased it ?

No it didn't have an emission or safety test. Safety wasn't a problem... my boss is a licensed mechanic so he did my safety.

I purchased the vehicle from Gatineau (Quebec). They don't have safety or e tests there.