My 1999 Dodge Caravan (FWD, 3.3L Flexfuel) is showing OBD2 diagnostic codes P0700 and P0731. The vehicle will not engage any forward gears, though reverse operates normally. I cleared the codes and retested the vehicle—no change; the issue persists and the codes do not return. What could be causing this? Is it a transmission internal failure or another component?
Jeff Compton wrote: The issue is likely inside the transmission itself. Clearing the codes does not resolve mechanical failures—this indicates an internal problem requiring inspection or repair. Thanks for that insight, Jeff. Could you clarify what specific internal components might be failing? For example, gear wear, clutch slippage, or sensor issues?
Possible cause: gear slippage. If the transmission case is transparent or equipped with an ESP system, visual inspection may reveal problems—but most 1999 Dodge Caravan models don’t have such features. In that case, internal damage likely requires removing and rebuilding the transmission or replacing it entirely.
Jeff, your explanation has a good sense of humor—though I appreciate the technical insight!
Thanks for all the input. I spoke with a technician at wellsve.com who suggested checking the Input and Output Speed Sensors. Since either sensor failure could trigger P0700/P0731 and result in no forward gears, I plan to replace both—each costs $18. Parts are arriving tomorrow morning; I’ll update the thread with results.
The techs at wellsve.com are helpful, but based on my experience working with Dodge transmissions over many years, faulty speed sensors alone cannot cause complete loss of forward gears. If you unplug both input and output speed sensors while the vehicle is running, it should default to second gear—only driving in 2nd gear. The absence of forward gears strongly points to internal transmission issues or a total lack of fluid pressure. Since reverse works normally, fluid level is probably not the root cause.
The issue is likely inside the transmission itself. Clearing the codes does not resolve mechanical failures—this indicates an internal problem requiring inspection or repair.