1995 Mercedes E320
Mileage: 128,000


We're having a problem with our 1995 Mercedes E320. It's seemingly an intermittent problem with exhaust-like fumes entering the cabin. The fumes were so noxious that we've had terrible headaches and neckaches. It's so bad that neither of us is willing to drive the car.

Our regular Mercedes shop and the dealership service department have told us that they cannot duplicate the problem. They have assured us that we do not have an exhaust system leak and that our emissions system is functioning properly. Further, they've told us that given the way the car is designed there's almost no way for fumes to get into the cabin.

We're at our wit's end and need help from someone.

Here's a summary of what's been done to the car recently:

7/25/08 - Regular Mercedes shop drove the car for several days, but could not duplicate or detect the problem with fumes. Read and cleared codes, cleaned MAF sensor, cleaned intake and added fuel treatment to tank.

8/14-20/08 - Regular Mercedes shop drove car for several days, but again was unable to duplicate or detect the problems with fumes. Replaced mass airflow sensor and air filter.

8/23/08 - Girlfriend drove the car on a short morning trip, and while stopped at a stoplight was suddenly overwhelmed with what could be described as exhaust-like fumes coming from the front of the cabin and exceptional heat radiating from the front floorboard and center console area. Girlfriend became ill with symptoms including headache, muscle ache and extreme nervousness. I drove the car on several trips around town later that afternoon, but did not observe any further problems. We parked the car outdoors overnight.

8/24/08 - I drove the car with girlfriend in the passenger seat hoping to duplicate and observe the same condition she had observed the previous day. We drove the car on several stop-and-go trips. During the third trip, the check engine light came on after about five minutes. Though no other symptoms were observed, we decided to drop the car off at regular Mercedes shop, hoping the codes would offer some insights into the problem.

On the way, suddenly the overwhelming exhaust-like fumes came flooding into the cabin and exceptional heat began radiating from the front floorboard and center console area. I stopped the car and had girlfriend get into the car to confirm that this is what she had experienced the previous day. Driving the short distance of less than a mile made me ill with immediate symptoms including headache, aching muscles, difficulty concentrating, and irritability--despite that I had opened the windows and sunroof at the first sign of a problem and turned off the air conditioning.

8/25/08 - Regular Mercedes shop said they could detect no fumes. They reset codes and used Power Clean fuel cleaner. Regular Mercedes shop said that if this didn't work, that we should take the car to the dealership service department.

I have put no more than 50 miles on the car since picking it from regular Mercedes shop. Each time I have driven it since, I've experienced noxious fumes and the symptoms outlined above.

The Mercedes dealership has had the car for observation and diagnostics for a week and cannot duplicate the problem.

Clearly, this problem is intermittent, but it is very serious.

...and what was the code?????????????????

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A Dalton

Good question. I was never told the actual code. I'll have to ask the first mechanic and post that. He and the dealership have been communicating--very collegial as I understand it.

Thanks for your reply.

A possible suspect is the AIR pump system is being activated when it should not be ...ask him if it is an AIR code. [ code 4]

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A Dalton

If you are at all handy, the codes are owner accessable on that chassis....

go here :

E320 16 PIN DTC Charts inc. pin 8, pin 14


Is the Check Engine light ON ??????????????????????

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A Dalton

The sudden and exceptional heat sounds like quite a clue. Heat is one thing and that would be odd enough. But for it to be "sudden and exceptional" combined with your immediate physical reaction really makes me think that exhaust is actually coming in the car.

I had a leak where the downpipe connects to the exhaust manifold on my car, and the symptom was that when I was stopped (not moving) and especially before the car was fully warmed up, I would get strong gas fumes in the car. There was only about a 1/8" gap (due to the fine quality Crapco cat converter I bought). But that small gap leaked quite a bit of exhaust. But not as much as what you seem to be describing.

Has anyone done a careful physical examination of the exhaust components at the front of the car (manifold, downpipe, back a couple of feet)?

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra

Here's an update on our problem E320:

After nearly two weeks with the dealership service manager, who could never duplicate our symptoms, I brought the car home and drove it on short trips around town with no obvious problems for nearly a week.

Then, on Friday evening on the way home from the office, the phantom fumes returned during a trip of fewer than two miles. The fumes began to affect me almost as soon as I pulled out of the parking space and the check engine light came on.

Monday morning I took the car directly to the dealership. The codes returned indicated an oxygen sensor malfunction and a problem with the upshift delay switch over valve. The dealership doesn't think these have anything to do with problem with fumes.

So far I've been more impressed with possibilities folks here on the forum have come up with than with the ideas from the dealership.

Does anyone have any other ideas, now that we know what the codes indicate?

Get a DIFFERENT MECHANIC. Do not go back to that dealer. Find a good indy or call up the local community college and see if they will take it on. If it was me I would really want to determine what those fumes are. Are they definitely exhaust? You could get a CO sensor from Home Depot and a small inverter from Radio Shack to power it and see if it goes off or not. If you go back to that dealer then you deserve what you get. I find it hard to believe the CEL at the exact time of the trouble is "unrelated".

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra

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Shift delay code coupled with 02 code , along with your complaint of doing it in the time frame as stated above would lead to the diagnostic conclusion possible of a leaking transmission shift delay cable element. That element is vac supply actuated and it only comes into play when certain criteria are met. The most important criteria are low temp. When the temp condition exist, the ECU sends a signal to the shift delay element in order to hold the trans in a lower gear for a short period in order to help heat the cat converter rapidly. This is an emmissions control system and that code would be a #26 on that chassis.
The offending 02 sensor code could be the sensors is reading this vac element leak as a lean fuel mixture b/c of the leak and it is trying to correct for that condition by enrichening the Air/Fuel mixture..but the leak can be large enough as to not be able to be compensated for, resulting in a very rich condition during this short , cold warm-up time frame. That is what you are smelling.
The test for such is to see if the element will hold vac when applied with a hand pump at the green vac line going from the Delay Shift valve behind the booster , going to the transmission.
That is the test which I would be interested in the results of before continuing on to anything else.
If this is suspect, you could also take the green line off the SOV and plug it with a BB, then put the line back on and see if the condition ceases. That would be verification of the diagnosis. That will bring the 26 code back , along with a CE notification, but you know that is just b/c you have temporarily disabled the Shift Delay system..[ for testing only]
If condition ceases w/delay diabled, you have again verified diagnosis.

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A Dalton

Has the engine wire harness been replaced? The high heat at floorboard implies the catalyst is overheating! This can only happen if the cat is getting too much fuel and oxygen. The car would produce huge quantities of rotton egg smell and maybe even raw gas smell.
Someone in a earlier reply to this post said get another Mechanic! I agree,Someone's not doing their job.
Mike Freeman