Hi, I am told by my mechanic that the never ending check engine light is staying on because I need catalytic converter. I have replaced all 4 oxygen sensors, all plugs and the car still doesn't have the pickup it used to. Where can I buy a catalytic converter on line that will be of good quaility and of course not too expensive.

Karen

 

Hi,
The check engine light doesn't come on because of faulty catalysts! It comes on when certain start up tests fail or due to numerous designated fault codes. Your dealer should be able to tell you exactly which code(s) have caused the CEL to illuminate since this data is held in the diagnostics system (subject to age/model). Once you know this information you have a chance of narrowing down what is wrong.
New plugs would suggest that there is a misfire (for which there is a specific code), new oxygen sensors would suggest incorrect O2 values (output can be observed through diagnostics) etc. Were these codes present?
I suspect your dealer is just picking the next possibility from a long list of possibilities AT YOUR COST!
Usual problems with catalysts are emmissions failure, cold rattle or lack of power. Does the car meet emmission standards? Have you been complaining of a rattle when the engine is cold?
It is possible that the catalyst is at the bottom of lack of power but I suspect not unless you fail emmissions or have a rattle.

MB catalysts are VERY expensive and dependent upon age and model of your car may not be available from anywhere other than MB.
If you are satisfied that the cats may be at fault get the dealer to remove them from the vehicle and see if it is possible to inspect them for blockage either by eye, with a fibre optic device or by passing a significant volume of air through them before parting with your cash. If they are blocked you have no option but to replace but this is unlikely
Hope this helps.
Stuart

 

there are catalyst efficiency codes. usually ends up being O2 sensors, but it could obviously be for the actual cats. ive replaced a few catalysts that have clogged up, the matrix breaks down and clogs against itself. if the clog is bad enough it will shut down the bad bank of cylinders, and suddenly youre driving a 3/4 cylinder. the catalysts pipe are defenitly pricey...

 

Hi,
Catalyst efficiency codes makes sense however this can only be for the pre-cat since O2 values are only taken upstream and downstrem of the precat.
The main cat only has an input O2 value. Its output is a tailpipe sniff which is not available to the onboard computer.

I've never seen a cat code so would be very interested to know what the code number(s) is/are so as to ensure my code dictionary has it referenced.

As you will be aware failure of a precat can turn out to be very expensive due to backwash of particles into the engine!

Stuart.

 

Hi,

I found the Cat efficiency codes in my dictionary although I've never seen them in real life. P0420 to P0433.

P0420/P0430 refers to warmup (pre) catalyst efficiency

P0422/P0432 refers to main catalyst efficiency. How can the system possibly know the efficiency of the main cat?

Is this possibly a reference to very early cat systems or the possibility that a code may be required someday in the future.
Have you actually encountered such a code?
Always something new to learn.

Thanks,

Stuart

 

Yeah, I was quoted $2000 for Cats with authentic parts and labor.

C

 

Stuart, do you think she might have a bad MAF sensor like me?

C

 

Hi,
BlueSilver,
The problem could be the MAF but it could be the injectors, fuel pump, knock sensor.......etc.
MAFs are relatively expensive at 300USD if you fit it yourself?

Need to narrow down the field .
The codes will give a good indication of what is wrong.

We don't even know age/type/mileage of vehicle etc.

I would agree that changing the MAF is the next possible option if DTC's can't be read but I would prefer additional data and get the diagnosis correct.

Stuart

 

Stuart,

I understand about the diagnosis.

The prices you quote are always much cheaper than I can get here. Product prices of inflexible demand seem to be doubling every two years here lately. Its probably just our currency diving in the world market.

My MAF was $525 USD, but I bought it at the big-city dealer, and it came in an a brand-new crisp MB package, with an unbroken security seal, and was the IDENTICAL/EXACT replacement down to the mold number, so I felt ZERO risk in buying the part.

Sometimes other local stores sell replacement parts for less, but there is ALWAYS some kind of regrettable compromise, such as it doesn't look anything like the original, doesn't fit properly, or requires some kind of cutting/drilling/modification etc.

I wanted you to know that I'm a 20 year car hobbyist, and during my career I have actually built manufacturing machines for MB, worked with an MB racing team, and owned my own machine custom shop for racing cars on the circuit, and still have machine-tools in the basement for hobby cars. But somehow MB always cripples me with their computer system. I build an excellent block but when it comes to the FI, I guess I just can't keep up. Thanks for logging in and bailing me out on the FI.

I did want to mention to ENDUST that testing the CATs by removing them and inserting an electric lawn-blower into the pipe, works great. It will not fix or restore the cats, but if air blows through....they're NOT clogged.

 

Hi BlueSilver.
I don't have access to MB pricing so have an indicative "guess". I'm obviously out of touch with the latest MB US pricing.
MB pricing is outrageous and bears no relationship to cost to manufacture etc. It seems to be based entirely on what can MB can get away with after recognising that most owners aren't short of a few dollars and don't understand what they are paying for.
I certainly don't fit this stereotype.