Rugger4lif

Recurring P0305 2006 Lexus LX470 with 166K....replaced Fuel injector, Spark plug and coil on cylinder 5. Was going to compression test cylinder next to see if it is an issue with valve or piston. Since it is not spreading to 0300 random I thought it would most likely be isolated to cylinder am I thinking too narrowly. Next steps checking plug for moisture. No real loss of power, no shaking, it idles a little rough then smoothes out once warmed up. Really hoping not a piston or valve as Very time consuming but doable. for me. Appreciate the guidance. Replaced Fuel filter - with OEM Fuel Filter, Denso ignition coil and Iridium plugs from autolite.

Puttster

Sorry I can't help, but am wondering about your "spreading" description. That seems to be hsppening to my coils. What is the cause and/or solution?

Rugger4lif

If you are getting a P0300 your problem is most likely broader meaning you are getting random misfiring from different cyclinders and you may get P0300, along with P0304, P0301, P0302 etc. I had this happen on both my 1995 es300 (279K miles)and 2000 RX300 (207K sold) . on the eS300 it ended up being I had a leak in my intake. Check out the posting in Club Lexus . Hope this helps

https://www.clublexus.com/forums/rx-1st-gen-1999-2003/206254-i-fixed-my-misfire-check-engine-light-p0300-p0301-p0302.html

toddmorr

leak in intake would make sense as it smoothes out after thorough warming up....materials would expand slightly to fill the leak.

Rugger4lif

Update - So its been a while and after extensive investigation.....The code would go away and return after a couple weeks with other issues. I brought the car to the only mechanic I trust and he revealed the culprit. Blown head gasket. I decided that we would replace the motor. I love this vehicle and cannot come close to same comforts and capabilities without a big monthly car payment. New/remanufactured motor is coming with a 3 yr 100K mile warranty so I figured I would do it.