i have seen that some people have substituted the o2 sensor from a 90 mustang 5.0 for the factory m103 sensor i found the bosch australia website that lists oem and replacement sensors for a zillion cars seemed like australia models go figure there is a cross reference at the end that lists #258 986 504 as the replacement for 0 258 003 146 (the number on the official mb part in my 91 300e) i went to my local autozone store to get the bosch number off the mustang sensor they had 2 different ones 0 258 003 942 and 953 the bosch catalog had neither listed but did list 0 258 003 950 the replacement for this is 258986502 the catalog lists many ford vehicles from around 1990 with 5.0 engine that would use this replacement number the mustang listed did not have the 5.0 the catalog states the 504 number refers to a 18 watt heating circuit the 502 number refers to a 12 watt heating circuit so it seems that the difference between the mb and ford 5.0 sensor is that the mb(504) will heat up quicker than the ford also the ford is slightly larger in diameter one other note the bosch catalog says not to solder the wires but use crimp connectors because the sensor gets reference oxygen(atmospheric) through the wires and solder may impede this

Not sure what you're getting at, but I have a mustang 5.0 O2 sensor in my 190E and I have had no problems....for 18 months, so if you are wanting to know if it works the answer is yes. It has/is working for me.

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1990 190E 3.0L

I had always heard the items were identical except for the connectors. But this plants a seed of doubt. Could it be the cause of my slightly high HC numbers. Hmmmm.

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'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)

I put the question to a Bosch rep before. He said that the differences are in the amount of current the heater circuit draws.....

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90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff

If the Mustang sensor draws 12w and the MB sensor draws 18w per rob m's research which is somewhat corroborated by duxthe1's exchange with the Bosch rep, then theoretically the Mustang sensor doesn't get as hot as quickly as the MB part. I assume this could have an effect on fueling.

I used the Bosch Mustang part when I replaced my sensor recently. CEL went off and the car runs as smooth as glass but failed emissions HC numbers by a small amount. I am not aware of any quantifiable difference in fuel economy.

Could this be definitive evidence of why it's necessary to buy the high-priced MB sensor? Has anyone with an M103 with any kind of mileage actually passed emissions using a spliced-in Bosch Mustang O2 sensor?

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'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)

Wouldn't this only affect the heating? Once warmed up properly by the car, would it still affect it?

Electrically most of them are the same and I think that most of them or the same thread size, if not there are probably only a few different sizes.

No reason not to.

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2001 SLK 320 six speed manual
2014 Porsche Cayenne six speed manual

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I used a Mustang Bosch sensor spliced in and I passed California emissions.