jfillis

Hi,

I bought a 96 ls400 cheap. Turned out the reason was the engine was bad. I bought a used engine put it in with a friend. It runs great but I can't get rid of the codes. It throws up P0125 and P0135. One of them is something about the thermostat sensor. The other is an O2 sensor, bank 1 sensor 1 I think. I put in a new sensor (pre-cat) but the code is still there. Not sure what to do about the thermostat (I did put a new one in). My cats sound kind of hollow. Could bad cats be making these codes come up? Any suggestions? I'm on my last temporary tag and need to get it registered so I can either drive it or sell it. Thanks

PureDrifter

iTrader: (10)

check the wiring on the o2 sensor, and search the forum for the test to see if the engine coolant temperature sensor is dead/bad.

jfillis

I will check both of those options. Still curious if the O2 sensor before the cat (very close to the cat) could be affected by a bad cat? Thanks for the info.

GS4_Fiend

iTrader: (22)

Oxygen sensor before cat measures the oxygen in the exhaust and sends a signal to the pcm to adjust the fuel trims. Oxygen sensor after the cat measures the efficiency of the cat. The purpose of the cat is to store oxygen, so if the cat is deteriorated, it will leak oxygen and the post oxygen sensor will detect oxygen and will trigger the CEL for cat efficiency below threshold.

As for the other code check thermostat and coolant level. Check for signs of corrosion when you disconnect the ECT. To test the ECT accurately, you would need to boil the sensor to 212F and check the resistance. But i would just change it.

jfillis

Ok. I have read several posts on the Engine Coolant Temperature Sensor but I am still confused about where it is located on a 96 ls400. Can anyone help? A picture would be great. Thanks

timmy0tool

iTrader: (7)

search harder!

https://www.clublexus.com/forums/ls4...ange-pics.html

jfillis

This is very helpful. Thank you