o/d light flashing, code 646

[bean440]

I have a 95 explorer that will not shift out of first gear unless you back off the throttle. Also trans slips when kick in passing gear.
The o/d light is flashing. and the computer codes are Memory code 646( gear 2 ratio fault) and Koer code 336 ( EGR pfe/dpfe volts higher than expected).
Has anybody had or seen this problem before? Does anybody know what these codes imply and could they be related.
Any help would be greatly appreciated!!! Thankx for reading this post!!

 

[Glacier991]

The codes are not related in any way I could imagine.

Tell me a little about the mileage, fluid condition, change interval, and history of any symptoms?

I have a sneaking suspicion that if you drop the pan you may have something in there.

 

[bean440]

The mileage is 88K, this problem developed suddenly and has never had any problems prier. I dropped the pan and the fluid was a little dark but not black. The pan had a very light film and magnet had small amount of sludge build up, no metal shavings or anything like that. As far as the change interval,I not sure I only have owned for about 8 months.

 

[rmmiller2050]

a 646 code was identified in another thred to indicate intermediate bands need to be adjusted - do a search on "646"

 

[rmmiller2050]

the egr codes are unrelated but common : i don't recall teh exact def for keor 336 but it could be something like the egr valve stem being stuck from carbon build-up. You might be able to disassemble the EGR valve unit and clean it and get it working again ( have to do this periodic on my F350 351cid Crew 4x4). Shorting the EGR valve position sensor terminals during engine-on testing should either make the "service engine light" come on or go off , if it has been on; depends on whether your EGR position sensor is normally open or closed.