MAS SWITCH,W126,300SE
 

I am still inspecting my newly aquired 1990 300se,almandine red!,that I just got for next to nothing(940$,1 owner car) and found the MAS next to the brake fluid reservoir with a 0-1 switch on top...whats that gona trigger if I turn it,better ask first.

mas switch
 

HaHA turning that knob detaches the mas from its connector , go ahead it wont explode!TURN THEN LIFT , if its stuck be careful. lou

MAS is a relay module that turns on the fuel pump, air injection pump, a/c compressor, trans kickdown, & the O2 sensor heater. Also processes the RPM signal from the EZL.

hi guys

found this thread when searching for info on mas.

whenever i start my car, the engine will rev very high (>3k rpm) for a few seconds before settling down to normal. this happens all the time, irrespective of cold/warm start.

finally found the cause to be the mas unit. it's quite an expensive part!

now that i got a faulty one, wondering where could i get this repaired? anyone?

thx!

yeo

Out of curiosity, how did you figure out it was the MAS?

In case you need a m.a.s unit,give me the part number and i most likely have the part.make me an offer
Thanks
Rich

how did i figure it was the mas?

swapped with a good unit from another 300ce. but of course, before that, almost everything have been checked by at least 2 workshops!

mine is a 008 xxxxx and i replaced with a 011 xxx but i'm just wondering if i could just repair my faulty unit and keep it as spare in case this problem crops up again.

yeo

It sounds like you got a good deal. When I got mine I changed all the fluids. If you have the service records check to see if the head gasket was done if not keep a close eye on your coolant reservoir for oil contamination. If you see any oil in the coolant you will need a head gasket. These are excellent cars; in the short time I have owned mine (since September) I only have had to replace the voltage reg., one lower ball joint, and the brakes. It needs a head gasket but still runs very good. I paid 200.00 for mine; it just goes to prove "you don't have to pay a lot to get a lot."

A good buy!
 

200 for a running 126? amazing value.
for utter reliability re-solder or replace the fuel pump relay ,known for its cold solder joints causing stalling problems as it ages.
mak
300SE