Getting codes 998 and 122.


Jul 25, 2019
Dayton TX
Have a 1991 Mustang Lx2.3l. When I do koeo test I get code 122. Tps sensor is brand new. Just replaced. Went ahead with koer test and got codes 998 and 122. Need help in the direction I should go.

When I tested my tps sensor I was getting a constant reading of 0.051 volts. Something turned on and the voltage went to 0.124 volts. No change when going to wide open throttle. Could the map sensor be messing with the numbers I saw they share a wire on a diagram. Honestly dont know what I'm looking at.
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Jan 10, 2011
That's not a MAP, it's a BAP. Does the same thing but doesn't reference manifold, only references barometric pressure (to adjust for altitude changes).

0.051v yes you should get a code. You may want to double and triple check that though. Also check for VREF, you should see roughly 5v on the orange/white wire. I don't like to ground the other lead of the DVOM, I like to use the signal ground from the computer, which is the black/white wire.

Your readings are odd. 0.051v is very low, as is 0.124. Check your grounds. There are quite a few of them; and one important one near the computer.