I have a 99 626 with a 4 cylinder engine and AT. It drives perfectly when cold but after a few minutes the transmission just slips like it is in neutral.
It had a p0421 code and CEL was on. I replaced both O2 sensors, PCV, sparkplugs and wires. Now no more CEL or codes. Voltage is 12.5v engine off and 14v running. Trans fluid looks good and is at correct level. It has a trans cooler. No vacuum leaks I can find.
Any suggestions?
TIA

 

When the transmission slips, make a note of the gear indicator light on the dashboard instrument cluster. If the D light is out, you probably have a linkage problem, which is how my 626 behaved. Come to a complete stop if you're moving, put the gear selector in Park and then back to Drive. Maybe even wiggle the gear selector as you put the car in Drive. This may solve the problem.

 

I recently replaced the gear box oil seal of my 1998 Mazda 626. The first test drive after the replacement, the 'HOLD' light started blinking, the rpms went up to 3000 at speed of 80 km/h, and the car couldn't accelerate after that. The gear shifted up to only gear 2 and there was this strong smell of burning metal. We put in more ATF, but the 'HOLD' light still came on(blinking), the first gear shift is rough, rpms still high at low speed, the engine temperature shoots up but the coolant is full. Surprisingly, driving at speeds of 20-30 km/hr the 'HOLD' light doesn't come on, but once speed is increased the 'HOLD' light starts to flash and engine temp rises. if I drive for a long time the car then decelerates by itself until it comes to a complete stop (even if I depress the gas pedal it doesn't move an inch!). I'm at a loss what could have gone wrong during the oil seal change because the car transmission was fine before, please assist urgently coz its the only car I have!!![/align]