Hi, I have a 2003 Merc C200. The emissions are really high but my mechanic is convinced that it is not the CAT but an electrical problem. We have replaced the front oxygen sensor and the temperature unit but to no avail. He says that the CO levels are too high for it to be a CAT problem. He has put through a few petrol washes to clear the engine of any debris that may have built up, but still too high. Any suggestions would be greatly appreciated.
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Re: C200 Emission Problems
Hello,good day,they already replaced some parts,but same problem,better to send your car to a dealer to diagnose with proper tester,they can evaluate your engine condition for emission test,also ask if you can get a copy of record,specially fault code,freeze frame data criteria,can be presented to emission officer,ty
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Many things can be the cause for high emissions. Dirty air filter, vacuum leaks, timing set wrong, wrong rpm, bad o2 sensor, defective egr, back cat. converter,sensors out of range ect. ect. It's highly unlikely anyone can guess and really help you. My best advice is find a good mechanic that deals in emission related diagnostics and have it professionally done. Will most likely be a lot cheaper than replacing a lot of parts that won't fix it.
You may need a mechanic. At least a shop manual.
The catalytic converter code means the computer does not think the cat is working right based on input from the O2 sensors. That data would need to be checked out and verified along with a temp scan of the cat itself.
The other two codes are saying the signal from the pressure sensor is too high and too low. The computer measures pressure inside the gas tank to make sure it vents correctly. The pressure sensor could be faulty, or it could be something else in the venting system.
Could be several problems: bent/crushed exhaust, emission problem, clogged catalytic converter, clogged fuel filter. Start by checking exhaust and replacing the fuel filter first. If not those, then you'll have to have a mechanic check emission system or cat converter.
The cat converter is mainly for emission controls. If you are in a state that does not due emission tests like I do(MN), you can remove that cat conv with no problems other than a little more polution.
looks that your catalytic converter is broken.Before you do anything take it to a qualified mechanic and request for emission test to see whether you do have high emission due to lambda sensor failure or cat. also you can check from your exhaust end if your emissions smell like rotten eggs.If so change cat.
The code means what it say. The car computer compared the data on amount of air/fuel injected in cylinders with the emission O2 reading from the Oxygen sensor in the air intake (the one after cat converter), and decided that the catalytic converter is not doing its job because emission is too high.
In some case the problem is occasional. Try resetting codes by disconnecting battery terminals (make sure you have stereo code if needed).
If the code comes back, then there are several parts to be tested before replacing cat converter.
Many times the problem is the converter itself. before replacing the converter the mechanic must check for problems resulting in wrong air/fuel mixture, as these may trigger p043.
Sensors in the air intake and air intake itself must be tested, check MAP sensor and intake structure for leaks. Replace air filter. Check the vacuum for leaks. Check IAC. Check O2 sensors.
If there is no problem under the hood, check the state of other parts comprised in the exhaust system and eventually replace the cat converter.
High emission are often consequence of engine problems. In that case the new cat converter or exhaust and new oxygen sensors will not help.
High emission from engine occurs because of many different reasons, main causes are:
Electronic injection problems:
Do an OBDII scan to find out if there are error codes. If there are no codes check injectors sensors in the air intake (MAF and IAC), check vacuum for leaks. Clean throttle body. Check EGR, IAC, PCV systems.
Engine internal problems:
Do a compression test to find problems associated with engine faults (eg.piston rings, head gasket, valves).
Also make sure that spark plug, fuel and air filter have been replaced. Make sure that there is no misfire or distribution problem.
Toyotas' are not known for cat.converters going bad. I would get a second opinion from another shop. (and don't mention what the first guy recommended) Have them do the scan and see what they conclude, 76 has good gas, I suspect you have bad mechanic..
That is a problem in the evaporative emission control system.
Could be anything causing it
Clogged filter in the charcoal canister
A leak in one of the vacuum lines
The purge valve not working,,,etc.
The best thing is to take it and have it checked out, they might have to do a smoke test to find the problem.
All they do is inject smoke into the system, if there is a leak the smoke will come out of it. All it takes is a pin hole in these emission systems to screw it all up.