I recently noticed that my 87 300e has no sensor in hole in the plastic scoop leading to the air filter. (The car has run great for the 12 months I have had it, until it refused to start this week, but that is another story, I think.)What does this sensor do, & should I get and install one? If so,to where does it connect? Thanks.

That's the intake air temp sensor. If you don't have the connector hooked up to the sensor, you'll get a check engine light. Either the sensor is hooked up to the connector and is dangling somewhere in the engine bay or it wasn't part of K-Jetronic in the 1987 model year.

I'll bet you're one of the lucky M103 owners with no EGR either.

Sixto
91 300SE
87 300SDL
83 300SD

I don't believe that vintage 103 engine has an inlet air temperature sensor. My '88 201/2.6 doesn't have one, nor does it have EGR.

Inlet air temperature sensors somewhere in the inlet duct are common on cars with speed-density EFI since inlet air temp and manifold pressure are the two primary sensed variables, but since the KE system has an air flow meter, it doesn't really need one.

Do later 103 engines have an inlet air temp sensor in the inlet duct? Anyone?

Duke

My 91 300SE does. I think it might be one of the differences between KE5-Jetronic and KE3-Jetronic. I don't think there was a KE4-Jetronic. Steve?

Sixto
91 300SE
87 300SDL
83 300SD

Our '90 300TE M103 has no intake air temperature sensor (or EGR, but it's Australian delivery too). My '90 190E 2.3 M102 has an air temperature sensor on the air filter that someone previously disconnected. I checked the manual and it shows that for my model year the M102 should have the sensor but in this case it is connected to the EZL ignition module not the KE ECU. Apparently the ignition timing gets progressively retarded at higher ambient temperatures. There were many subtle changes from year to year.

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107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.

I also have a 91 300e, and it has the air temp sensor in place. Is it possible that the plastic scoop leading to the air filter on the 87 is a replacement part from a newer model? Its hard to imagine why someone would need to replace it.

No sensor on mine.

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1986 300E 5-Speed 240k mi.

No sensor on my '87 300E...

Thanks so much. One less thing to spend $$ on.
Rich

My 1992 300E 2.6 (non-CA) is giving me a code of intake air temperature reading is illogical. Problem is, I don't see any sensor in that hole upstream of air cleaner, and no evidence there ever was one (no sensor wires in the area). Can anyone shed light on this? Thanks!

My 1990 300E does have the sensor. Replacing it actually made it run happier. (old one tested way out of spec, it was toast)

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I asked the same question a few months back, and the best guess is that the sensor wasn't added till about MY 1990, even on Calif version M103s. The FSM is very confusing on the subject, because it indicates that the sensor was added as a production change some time in 1986, but this is contradicted by everything I've been able to determine.

What happened to the Air Temp Sensor on my M103?

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1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't

From the last two posts, it looks like my 1992 300E should definitely have this sensor. Now I just need to figure out how to wire one up. I am wondering if someone might be able to take a pic to show me where the sensor wire routes to.

My '91 124 has the sensor in the air intake. My '90 does also.

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2012 E350
2006 Callaway SC560

Neither my 87 260E nor my 88 300TE has it. Interesting thread. I am watching for a definitive answer to this.

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