Hello,

I just replaced the O2 sensor on my '86 300E (Manual). Once the engine warmed I measured the duty cycle to check it out. It reads a fixed 17% . I guess this means we lookup 20% fault code which point to the throttle valve switch.

I stopped the engine and tested the Throttle switch by measuring the restistance between pin 2 and 3. It shows infinite . My understanding is that if I depress the plate I should get about zero ohm, but the resistance does not change.

Is this the proper way to test the throttle valve switch ?

Also, (this might be related), I am reading a constant 940 mv on the output of the O2 sensor. As far as I know this shoud fluctuate around 400 mV if the mixture is set right.

Any insight will be appriciated.
Thanks.

__________________
Zorin

'88 Benz 420 SEL
'79 Porsche 911SC ('87 Carrera Engine)
'00 BMW 540 Sports Package
'99 Land Rover Discovery

86 300E - Manual (sold)
88 260E (sold)
84 944 (sold)