so just yesterday, my check engine light came on...
seemed to be running fine, however if i stayed at a constant speed (55mph) it almost seemed like there was a miss periodically...speeding up or slowing down eliminated this problem.

so i had the codes read today, and here's what they said.

p0123
throttle position sensor high
p0456
small leak has been detected in the evaporative system
p0740
engine is running faster than it should for these speeds.

like i said, other than the wierd miss thing at a constant 55, seems to be running great...
the idle does not really seem high,
however at times, the trans seems to shift prematurely into OD
i'm a pretty non-agressive driver, so i'm generally pretty light on the gas.

anyone else have these codes show up on their xj??

i've put about 10 miles on this since the codes have been cleared, and the light has not come back on...

just wondering what the deal is!

thanks in advance for the help!!!
chris

 

1. sensor might be on its way out
2. Check the evap lines, one might have a a break or something causing a leak. my ranger threw one of those, hose was wasted and came off the canister

 

anyone else ever have these codes appear?? no issues on my drive home tonight...seemed to be running like a champ.
could it have just been a sensor malfunction/glitch throwing a code??

the only other thing i can think of, is that for the first time i used the cruise control...is it possible that the cruise malfunctioned and caused the codes??

kinda stressing about it, as i really don't wanna have to replace the torque converter.

help please!!!

anyone, anyone??

 

well have they came back after you had them cleared yet?

 

nope, driven about 100 miles since the codes were cleared, and they have not returned...
i'm thinking it may have had something to do with the cruise control...also have been driving a little more agressively, since the codes were cleared it seems to have a little more pep to it!!!

 

i have an 01 xj as well. last week i got a p0121 p0122 and a p0123 while coming back from a road trip. it did it on the way down, then on the way back a week later. replaced the tps and is fine so far. no weird "missing" while at a constant speed. as for evap, did you make sure your gas cap was on tight? this code appears because of that on certain occations.

 

I am getting one of these codes in my 1999 Cherokee Sport with 4.0 4 wheel drive, and automatic transmission. I am getting the P0740 code and P0700 codes. Replaced the Transmission fluid and Transmission filter and am getting better smoother shifts, however still getting the codes