Transmission slipping in your 2016 Kia Optima combined with a P0700 code indicates the transmission control module has logged a fault requiring diagnosis. The P0700 is a generic alert that additional transmission-specific codes exist, requiring deeper scanning to identify the actual failure.
Understanding P0700
P0700 doesn't specify the problem—it merely alerts that the TCM has recorded fault codes. A scanner capable of reading Kia transmission codes (often requiring enhanced OBD-II capability) reveals specific failures like solenoid problems, clutch slip codes, or pressure faults.
Common Causes of Slipping
The 2016 Optima's A6MF1/A6LF1 6-speed automatic experiences slipping from worn clutch packs, degraded transmission fluid, failing shift solenoids, or valve body wear. Low fluid level from external leaks also causes slip symptoms as clutches can't develop proper clamping pressure.
Fluid Condition Critical
Degraded fluid loses its friction-modifying properties, allowing clutch slippage that generates heat, further degrading fluid in a destructive cycle. Fresh SP-IV fluid and filter service can resolve mild slipping caught early, before internal damage progresses.
Internal Component Failure
When fluid service doesn't resolve slipping, internal components have likely worn beyond acceptable limits. Clutch pack friction material glazes and wears thin, solenoid bores develop wear affecting pressure control, and valve body passages accumulate debris affecting fluid flow.