Mercedes Benz 1989 300E Catalytic Converter Help. - PeachParts Mercedes-Benz Forum

vexman2k3 · #1 07-31-2007, 11:11 PM

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.

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.

Bruno_300TE · #2 08-01-2007, 12:08 AM

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

vexman2k3 · #3 08-01-2007, 01:04 AM

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.

Bruno_300TE · #4 08-01-2007, 04:21 AM

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

vexman2k3 · #5 08-01-2007, 05:12 AM

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

manny · #6 08-01-2007, 11:54 AM

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.

vexman2k3 · #7 08-01-2007, 01:05 PM

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

mpolli · #8 08-01-2007, 01:22 PM

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

mpolli · #9 08-01-2007, 01:26 PM

Quote:

Originally Posted by vexman2k3

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

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

david s poole · #10 08-01-2007, 01:46 PM

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.

vexman2k3 · #11 08-01-2007, 03:27 PM

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?

mpolli · #12 08-01-2007, 03:44 PM

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

vexman2k3 · #13 08-01-2007, 04:00 PM

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.

manny · #14 08-01-2007, 05:03 PM

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

vexman2k3 · #15 08-01-2007, 05:09 PM

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.