I got the dreaded check engine light again today.

1993 W124, 3.2 liter M104 engine, about 138,000 miles.

I checked the LED display and got a #4 code and a #26 code.

#4 seems to be Air Injection Inoperative.
#26 is upshift delay switch-over valve open or shorted.

I was plagued with the #26 code until I changed the valve and cleaned out the vacuum line. I can't believe the valve could already have gone bad or the line could've plugged up again. The part can't be 6 months old.

Is #4 as obvious as it seems? Does it mean that the Air injection pump that runs for 45 seconds on cold start-up has broken?

Thanks in advance.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".