i had the same CEL code for my 98 zetec had it about a year. took it to firestone they said they couldnt find the problem. about two weeks later car died and this was the result of the P1381.
Fuel in my oil = oil change
Fouled spark plugs = new spark plugs
and the kicker i needed a new VCT solenoid
final cost = 516.31 to repair.
