1987 Mercedes-Benz 420SEL Oxygen Sensor

 

Ok, so you sell parts... what real help can you offer the gent? He has an Sl, not an SEL. I take it he is in the UK, since he converts UK price to dollars... I consider your reply as spamming the forum.

To the original poster, perhaps the new exhaust was installed without an O2 sensor bung, and the sensor was eliminated. If so, install a bung in the pipes where the cross-over is, or where ever the streams come together, and wire in... electrical diagrams should be available in the manual.

 

Firstly Guy (or is that Mr Wlaker?), find a new mechanic.

Secondly, that link posted above wont help, the 420SEL one is different.

OE Bosch one is about USD$125.00. Just have to get it to the UK. If you want to save a few quid on shipping Dave might be able to help.

Where in the UK are you located? (just for interest's sake).

 

Seems to me that issue isn't the O² sensor as much as finding someone to weld the proper fitting into the exhaust. Did you add the current exhaust system or was it the work of a PO?

 

Thanks for the responses. The stainless steel system was fitted by a previous owner and I think they just cut the whole thing out and when the engine worked returned it to the lady owner.
I am based in London and know the part number MA009 542 39 17 which may be different to the 420SEL in the US due to the emissions control being more lax here. If that part can be got for $125 in the US then I am interested. I'll happily pay shipping and stuff.

I think the fitting needs to be 22mm threaded hole but I will get the part and measure it before finding where it can go and drilling. As for wiring - I will get to that later. There must be something around that can help on the web.

Finally - ye sit is Guy and my last name is Walker. My cryptography skills aren't what they were.

 

Just an update. I have found an O2 sensor for $75 through a non MB parts company. Ordered and now to fit the thing.

 

wire diagram

According to the diagnostic manual, it groups the 1986 and on 116(4.2) and the 117(5.6) in the same chapter. Here is a wire diagram of the CIS-E injection system, model 107. I think this includes yours. Can anyone confirm this.????

 

That is great - once the Bosch sensor arrives, I will investigate whether the two plug connectors are still there or not. I would imagine that the wiring would be the same but the settings and the actual components might be different in a UK car vs a US one. Thanks a lot for your help on this.

 

Here's some more info that I found, and I think the plug should be located through a access plate on the passenger floorboard area, come on 560 owners,a little help here...
can you tell i'm board today....

 

The new sensor should have a grommet on it. Make sure you position the sensor where the grommet can fit into the hole in the transmission tunnel.

 

Here are a couple of pics from the outside, showing the threaded exhaust fitting's mounting location and cable routing of the O2 sensor on an '87 US-market 560 SL.

Good road,

 

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Post #21

 

I have read that a 1990 Mustang O2 sensor works (40 bucks at Autozone). Do a Google search on Mustang O2 sensor in Mercedes or 560sl. Just spice it in. Have not tried it yet but would do so if and when mine fails.

 

Thanks for this. My car has no catalyst but I have found that it is just before the first silencer box (only just not on my particular car). Its on order so once in I will drill and thread the hole and hopefully plug it in using the diagrams. I'll let you all know how I get on. Thanks again.

 

You can't just drill and thread the exhaust, there's not enough material. Any muffler shop can install a threaded bung to accept the sensor...