Dmoszek01

Hey everyone. I got a problem with my '03 Lexus ES300 (3.0 V6). Bought the car at 205k miles, and after 10 months it's at 246k. Never had any bigger issues until recently. I had power steering leak and code for knock sensors, so I found a guy from my friend who fixes cars on the side (also my MPG been down for some time now, but thought it's not a bigger issue since the car is old). I bought my own parts, and had him replace the pump, hoses, gaskets, coolant bypass hose, knock sensors and harness plus the spark plugs. Car drives perfectly fine, no leaks, even MPG got little better, and the car has more power. Unfortunately now when idling, car slightly "vibrates" every few seconds and RPM's go to 800-900 (if AC is turned off, it's almost normal, but I can still feel very small vibration from time to time). Also it threw a code yesterday (when I picked it up), for misfire in cylinder 4 and P2241 - low voltage on o2 sensor. I erased the code, and only o2 code came back. Today I got another code for other bank o2 sensor (P2238), and misfire for cylinder 5 (4 still did not show up). What could possibly be wrong? Are the spark plugs faulty, causing engine to run rich and making the o2 sensors to throw a code? Not installed correctly? I would really appreciate anyones help. (FYI spark plugs are iridium Denso) Thank you for any insight and your time.

LeX2K

Where did you buy the spark plugs? Almost all of them out there are fakes. Your other codes could also be caused by poor quality parts please list exactly where you bought them.

Dmoszek01

I got them at rockauto. Spark plugs are iridium Denso.