My exhaust emission warning has totally refused to go. took the car to the dealers and they replaced the massairflow sensor. After a day or two the light was back on. the car is a VW Passat 2003 1.8 T

The warning light more times than not is coming on because of the emission system. There are several sensors that are hard to diagnose even for a professional with a computer. First place to start which is cheap and easy is to use a fuel treatment for a few tanks of gas. This has worked for me in the past by cleaning out the fuel injectors and fuel system. From there if this does not work you will have to check O2 sensors everywhere they are and replace.

yes

Ho Joanne:
On Grand Cherokee oxygen sensor locations for 4.0 and 4.7 engines, check this diagrams...







The Oxygen Sensors (O2S) are attached to, and protrude into the vehicle exhaust system. Depending on the emission package, the vehicle may use a total of either 2 or 4 sensors.

Federal Emissions Package (4.0L and 4.7L engines):
Two sensors are used: upstream (referred to as 1/1) and downstream (referred to as 1/2). With this emission package, the upstream sensor (1/1) is located just before the main catalytic convertor. The downstream sensor (1/2) is located just after the main catalytic convertor.


California Emissions Package (4.0L engine):
On this emissions package, 4 sensors are used: 2 upstream (referred to as 1/1 and 2/1) and 2 downstream (referred to as 1/2 and 2/2). With this emission package, the rear/upper upstream sensor (2/1) is located in the exhaust downpipe just before the rear mini-catalytic convertor. The front/upper upstream sensor (1/1) is located in the exhaust downpipe just before the front mini-catalytic convertor. The rear/lower downstream sensor (2/2) is located in the exhaust downpipe just after the rear mini-catalytic convertor, and before the main catalytic convertor. The front/lower downstream sensor (1/2) is located in the exhaust downpipe just after the front mini-catalytic convertor, and before the main catalytic convertor.


California Emissions Package (4.7L engine):
On this emissions package, 4 sensors are used: 2 upstream (referred to as 1/1 and 2/1) and 2 downstream (referred to as 1/2 and 2/2). With this emission package, the right upstream sensor (2/1) is located in the right exhaust downpipe just before the mini-catalytic convertor. The left upstream sensor (1/1) is located in the left exhaust downpipe just before the mini-catalytic convertor. The right downstream sensor (2/2) is located in the right exhaust downpipe just after the mini-catalytic convertor, and before the main catalytic convertor. The left downstream sensor (1/2) is located in the left exhaust downpipe just after the mini-catalytic convertor, and before the main catalytic convertor.

Hope this helps; also keep in mind that your feedback is important and I'll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using Fixya, and have a nice day.

Your code is a lean engine code. Need to have the O2 sensor checked. Possible vacuum leak. Common problem with these cars is the massairflow sensor. This can be verified with the use of a scan tool. More than likely you have a massairflow problem.

If you paid the Dealer to find out what was wrong (why the light was on), he should have told you. If you paid the Dealer to fix the problem, you should not have the light on now. Either way, if he has your money, you should either know what needs fixing or what he fixed. Go back to the Dealer and get what you paid for.
If of course, you took your car in for a service and you haven't been charged anything extra, then chances are nothing has been done.
Most Dealerships are normally phoning customers back saying this needs doing or that needs doing, after you have taken the car in unaware that anything needed doing (mostly it doesn't either).
Even without mentioning a "Check Engine" or emissions warning light being on, this should have been picked by any self-respecting mechanic, and an assurance may have even been sought from you that were aware that they hadn't done anything to rectify it before you took the car.
Having said all that, the most common problems with emissions and/or check engine warning lamps being on (in general - not just Suzuki) would be from oxygen sensors and cat converter temp probe failures. These sensors sit quietly in the exhaust system baking away at 1000 degrees telling the ECM it's running too rich or lean (O2 sensor) or that the cat convertor is too hot (usually after its been running too lean!).
Go back to the Dealer and find out what has failed. Don't tell him to fix it (unless you've already paid) as some of these sensors can be many hundreds of dollars.

It may be the computer itself. If the light keeps returning, either the computer is faulty or the fans are really failing. I do not recommend dealers but actual mechanic shops.

The Exhaust Emission Light can come on if the car is driven slowly over short distances.It will not happen on cars driven at speed. A short trip of ten miles at over 3000 revs should reset the warning light,although it may not go out for a couple of days after you have tried it . Hope this helps and saves a bill at the local dealer. JK

Catalyst Effeciancy below threshold (Bank 1) is the code meaning. Check or replace the oxygen sensors. Some cars have 2 .One is on the front of the cat. the other is the on the back. Check the back sensor . Other possible causes are leaking or damaged exhaust manifold, bad coolant temp sensor.If toyota did not replace both . replace the one on the back of the Caty.

i have a renult scinic 2004 1400cc emissions warning light on running uneeven and loss of power can this be sorted out what is it

I had a similar problem on my 95 jimmy. It was something that took a lot of time and money to diagnose, but now 3 years later...no proplems. Emissions requires the truck to have an EGR valve (exhaust gas recycle) and this deposits gunk (carbon residue) on your MAF (mass air flow sensor) If you catch it in time you can use a carbon cleaner from Autozone or checker Lightly on the MassAirFlow sensor. If not in time you may have to have either the MAF or EGR valve replaced and these are expensive. After a long period of time being undetected eventually the EGR valve will start smelling like sulfer, this means its to late to clean and save!

Hope this helps