Emission control system
I believe this information must be useful to most cars manufactured from year 1997 to maybe 2008. And if you have a Mercedes SLK R170 with a 320 engine it's almost exact the same. V engines normally have four O2 sensors and inline engines two O2 sensors.
5, Exhaust system:
Now I have to take a look on the downside of the car and its exhaust, are there any leaks or other damage to it? Of course I should have done this much earlier, but when doing all repairs outdoors on a parking lot it's not so easy.
Here you see the front part of the exhaust and its four catalytic converters. The first two almost hidden on the sides of the gearbox. The front of the car is to the right.
The upper exhaust is the right side and then bank no 1. The lower exhaust is the bank no 2.
The two rear catalytic converters. As you see it's in mint condition and I couldn't find any leaks.
What I know the front part of the exhaust with its four catalytic converters are the same as the Mercedes SLK (R170) 320 car. The rear part is different and special for the Crossfire, from this joint and to the back of the car. Check carefully if you try to replace it with Mercedes parts!
It's exiting to look under the car, I can't see any rust problems at all, I sprayed some rust protection on the few places where it were some surface rust.
The bank 2.2 downstream O2-sensor. As you see the electric connector isn't correctly fitted together (yellow gasket visible), my mistake after I had replaced the O2-sensor. The left side, the driver side (not English cars).
Of course I got an error code from this when starting up the engine, the P 0141 error code. It says that Bank 1 downstream O2-sensor is faulty. But what? This is the Bank 2 O2-sensor! I had to discuss this with a friend before taken action.
Is this what has caused all my problems, some earlier owner or workshop has shifted the cables for the left and right O2-sensors?
The right side and then the Bank 1 down stream O2-sensor.
Here you see the two new O2-sensors mounted, the old ones looks to be the original ones, never replaced before.
You see the cable coming from the computer box and it splits like an Y to the two connectors. When I tried to change the left and right side the cable to the left side was to short. Was it really anything wrong with the connections? After a closer look I see that the two cables was of equal length, but one was shortened with a stripe. I cut the stripe and connect them as how they should be connected according to the error code I got.
Now when everything was finished I did a test run. Normally I have a MIL light up after 16 miles but sometimes not. The odometer show 15, 16, 17 miles and continue without any MIL light up. Now I had driven 55 miles (88 kilometers) without any problem. It looks that I have fixed the problem! Later when I know everything is correct I will protect the cables from water and dirt, they are a bit exposed down here.
This is very strange, could it been default already from the factory? My friend has a theory, in the beginning when the engine is new there is no difference between the bank 1 and bank 2 cylinders and then it doesn't matter if the cables are shifted, but when it get older there will be difference and then it matters. But most likely someone has shifted the cables and restripe them to fit, but why?
Guess who's happy today :-)
This problem didn't cause any big engine problem, the down streams sensors just make very small adjustment. The car passed the emission test with out any problem already before. But if the engine is worn out, the difference may be greater.
If you think you have a similar problem, just disconnect one of the downstream sensors and see what the error code say. If it refer to the wrong side then it's likely that the cables are shifted. The upstream sensor I don't think will be mixed up that easy.