My check engine is on and the codes that I get are 35 & 55 - what do these codes mean

Still may have codes in the systems

Best to go for a road test with a scanner
& look at & record all data.

I would say 100% of all drivability testing is done
from 35 to 58 mph & I personally seldom drive 70
& won't get in a vehicle driven by anyone doing so

Point being-- I think you can find the problem without going
past 55 mph,you just see the MIL Lamp at 70 plus,the issues
have been there for months, most likely

I can help you with the codes but i need to know what scan tool you used, or for example you used a code reader or some other way, i just need to know how and also the year,make and model with the engine size.

okay, 1998 voyager these are not obd2 codes, these are genric codes, you used ignition to get these .
these codes are for older models that use codes like these 12 35.
the newwer obd 2 use codes like po 013. i will try to see what i can find, also the engine size is important.

okay here we go, the first code is 12, this code means the battery was dead or dissconnected.
the next code 35. this code means loss of prime, code # 11
means internal transmission failure.
the code 55 means gear ratio error.

these codes would tell me that you have transmission problems. this may mean internal trans failure and a rebuild or replacement transmission is needed or shift pack needs replacing. anyhow i would have a shop check this out, these van are known for transmission problems. hope this is helpful good day

Do you have an auto zone nearby? they have a small hand held computer that will hook up to your car & tell you what those codes are.

Have you tried cycling key, to on, off, on, off, on, and leave on and count the flashes of the check engine light?
(Just to on, not start) This should retrieve any trouble codes. Write them down & get back to us. It will be 2 digits and will work like this example: 2 flashes, pause, then 2 more flashes= code 22. 3 flashes,pause then 5 more flashes would be code 35. Code 55 means end of message.

The trouble code that you gave is not a code. If it 35 its the radiator fan relay circuit. The 55 it means end of fault reading mode. Recheck code. Going to local autozone they will check it for free.

Turn key to on, then off, then on, then off, then on & leave it on, (not start, just to on) then count the number of flashes of check engine light. It will flash,then have a small pause, then flash again. It will be a 2 digit number, for example: 2 flashes, pause, 2 more flashes, will be code 22. 3 flashes, pause, then 5 more flashes would be code 35. When you get 5 flashes,pause, then 5 more, That is code 55 which just means end of message. Get back to us with codes & we'll advise of what to look for.

You can find out at a part store by either asking somebody or looking through a Chiltons/Haynes book on your make, model, and year.

Cycle key, on, off, on, off, on, and leave on (not start) & count "check engine" light flashes. Always a number, a pause, then another number. For example: 2 flashes,pause, then 2 more is code 22. 3 flashes, pause 5 more, is code 35 etc. When you get 5 flashes, pause, then 5 more, that's code 55 which means end of message. Try that and lets see if any codes come up & go from there. Get back to us with what you find.

Sounds like you need to check for a vacuum leak.(hissing noise) Also try this,: Cycle key, on, off, on, off, on, and leave on (not start) & count "check engine" light flashes. Always a number, a pause, then another number. For example: 2 flashes,pause, then 2 more is code 22. 3 flashes, pause 5 more, is code 35 etc. When you get 5 flashes, pause, then 5 more, that's code 55 which means end of message. Try that and lets see if any codes come up & go from there. Get back to us with what you find.