If the P-N-P sensor were malfunctioning, you'd have the trans. MIL lit on the instrument panel and the WES mode switch lights would be flashing. The trans would sometimes/always start out is 3rd gear rather than 1st gear. Sometimes, the reverse lights will not come on when in Reverse. Sometimes the vehicle will not crank unless you move the shift lever around while cranking. Some or all of these symptoms can occur. As a temporary fix, you can "Row" the shifter all the way from Park to Low about 20 times (key ON, foot on the brake and engine OFF)

It's a common problem on these vehicles and I've had to replace them on both our 95 964 and our 98 S90

DEWFPO
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1998 S90 083,228 and 1995 964 154,100