95 E320 Wagon check engine codes evaluated
 

I have a check engine light on and from postings I figured out how to extract the codes using the push button procedure whee the number of LED blinks correspond to the code. The following two codes are indicated


4: is air injection inoperative
20 is speed signal not present.

Any help in further diagnosing the problem would be appreciated. Is it unquestionnably clear what the problem is and what should be done to correct this issue or is further diagnosis required?

thanks.

Check your vacuum lines from the Air system switch over valve back. I had a CEL and similar codes, replaced about 6 feet of bad vacuum lines, cleared the codes and they have stayed cleared.

Is your speedometer not working? Speed sensor will set a light. The engine computer needs that input.

Clear the codes and see which ones return. It's not unusual to get spurious codes or hiccups.