long term fuel trim

[rammit11]

Hi, I have a question on the fuel trim. I have the innova scan tool and it is showing my ltft at 22%. I have apprx. 200 miles on the engine and it also today threw a 0420 code. I am thinking the code is from a faulty rear o2 sensor ,will be getting that fixed asap. Will that sensor cause the high ltft or are my injectors on the small side. I have the neon 703 injectors and the vehicle is a 1998 xj 4.6 with a calculated 9.25 compression.

[SilverXJ]

Yes, a bad O2 sensor could cause both the CEL and excessive LFTs. How many miles on the current sensors? I wouldn't isolate it to just the rear sensor. If you haven't replaced the front one, which is responsible for the majority of the fuel trims, I would replace that as well.

[rammit11]

Thanks silver , I did have to change the front one as I managed to drop a piece of steel on the pipe and cut the wires. The rear I would say as a guess( been a while since I put it in) has around 60-70,000 on it.