So, I hop in my 92 400e this mornging, and to my delight, the check engine light turns on. I've heard a lot of times the o2 sensor goes out around 80k miles (mine has 85k), but I am not too sure what the problem is. The car still runs like it did before (which is great). So, any ideas on what it might be would be great. Thanks a bunch.



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Kyle
1992 400E Emerald Green

you need to try to get someone to walk you through reading the "code" to verify but I would bet it is the O2 sensor. I just replaced the one in my '95 E320 with around 85,000 miles. Same thing, light was on one morning and car ran great, got good gas milage and the light stayed on anytime the car was in use until I replaced the O2 sensor.

I do not know if the E430 has the built in code reader but I will explain it on the E320. Right in front of the battery is a little rectangular black box with a bunch of holes in it (It may have a cover over it, lift it off if it does). Looks like you could put a Fluke meter probe into them.
At one end of the box is a red LED light and a push button. Put the ignition in the "on" position without starting the car. Hold the push button down. When you first push it down the red LED will turn on then go off. Keep holding the button down. If there is a code (there will be) the light will start flashing. On the E320 12 means that the O2 heater circuit has gone bad and you need to replace the O2 sensor.
If you need help on replacing just let me know.
good luck
engatwork

Great, thanks for the info. I really hope it is just the O2 sensor! I'll give it a try and see if I get the 12 flashes, and let ya know.

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Kyle
1992 400E Emerald Green

Unfortunately the method is exactly the same but there is no LED on the 92 400E. If you want a further description you will need an LED, a DSO, or a logic probe or an impulse counter or scan tool. If you have any of the above let me know and I'll run you through the technique for whichever you have.

ok, well, I think I can find an LED around the house, or just pull one out of an old toy or something. Is the process much different than the E320? Thanks for the info.

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Kyle
1992 400E Emerald Green