Sponelis

Unfortunately, I am not that knowledgeable myself to check these things. I only go by what my mechanic is telling me. When we changed the lower 02 sensor (to an aftermarket one) couple of months ago, he said that is showing wrong readings when car is idling or on low revs, but when you drive the car normally it is showing correct readings. In the other garage, the guys said that my fuel trims are -15 and should be around -4, but again this can be due to faulty lower 02 sensor or cat. So I am a bit stuck on what to do next. My original mechanic thinks that its cat and it cannot be that the new sensor is faulty, other garage thinks it could be a sensor, and the third garage just said its cat... Car runs smoothly, no misfires, nothing. But sometime i get the other codes that i mentioned. I am trying to take to one more garage who worked on Lexuses before, maybe they will help me there. It's just a shame that mechanics want to change the part straight away without spending enough time on the car to eliminate other possibilities..everyone is just too busy.

My mechanic just came back to me saying he could not find a hole near 02, so it must be the cat then..

It’s 125k miles. I have asked my mechanic to look for leaks. I also was getting knock sensor code P0333, and codes P0172 and P0175. Other garage told me it’s all related to the fuel mixture as cat is failing. Would these be caused by a hole in an exhaust? Someone also suggested to install 02sensor spacer to get rid of this. I have no idea what that is, would that solve the problem?

Hi all, Couple of months ago I got an error P0420 - Catalyst System Efficiency Below Threshold Bank 1. Changed 02 sensor but that did not fix it. Two different mechanics are saying its the cat gone bad. It is the upper cat connected to the manifold and it is impossible to find one. Anyone could suggest where to start looking for one? Can it be deleted? Any advise at this point would help as I am pretty desperate by now. OEM part is too expensive.

Hi Mr Vlad, I use E5, car drives perfectly fine, however couple of times I had revs going up and down on its own when idling and then it stopped after like half a minute. Haven't seen any smoke from exhaust, apart from early morning on cold start, which I assume is normal. Lights have been cleared by my mechanic today, I drove circa 40 miles afterwards and it hasn't reappeared yet. Ill try to clean MAF. I could try the additive as well, but my mechanic said it shouldn't be anything wrong with the injectors as error code is appearing on both banks, meaning something else triggered it.

Hi all. I have got Lexus IS250 2007. Couple of days ago check engine light and check VSC came on at the same time. My mechanic tried to diagnose the car and got codes P0172 and P0175, both banks are too rich. He did some more tests and the long term fuel trims were showing -25. All of the sudden something happened to the engine and fuel trims became normal. He is not sure what is causing it. Reading the forums, everyone is saying MAF sensor, but he said it can’t be as he was getting good reading from it. Anyone has any suggestions what could it be and what to do next to identify the problem?