Had a trouble code for 02 sensor, replaced 02sensor and code cleared, then had a misfire cylinder one appear. The cel was blinking. 2001 Lexus RX300

Now what?

 

Time to pull out Plug #1 ... passenger side, next to the firewall.

You can swap it with a working [#2 is easiest passenger side towards the radiator]. Next would be swap the coil between 1 & 2.

If you have more than 110K miles since spark plug replacement, I would go ahead and put in fresh ones. Stay with OEM plugs and coils.

Salim

 

Put the old sensor same problem.
I had the battery disconnected right now. I'm going to hook it back up and see if that helps

 

Had all the coils ,plugs, timing belt, valve cover gaskets done all work done at the dealer

 

Everything's been fine for about a thousand miles after I had all that work done. They also did the AF sensor

 

You are right to suspect new problem to the last work done, but at times you have to step back. If the new problem has multiple paths then they should all fail. Misfire in only 1 is odd. That is why I suggested to treat it a separate problem ... specially as it can be checked fairly easily [with flex drives and adapters number 1 is not too bad ... you need slender hands for #3].

Salim

 

Your answer is correct. I just didn't want to hear that. I have an old coil. I have the old plugs that I know are good. I'll just swap.
Glad to an answer, was wondering if you can still get mechanical advice online. Thanks much

 

I have big hands but I was able to put my old coil back in. Problem appears to be gone for now.
Every genuine Toyota parts can be defective. I really hope coil three and five hold up because those are pretty hard to swap out

 

Agreed! While some of the aftermarket stuff can work, but RX is finicky when it gets to sensors and electronic modules. There is also a large market of factory seconds and fakes. I have never been bit by parts I buy from dealership [either in town or net sellers]. I know it costs more, but my saving is in DIY and not worth the trouble of testing parts of suspicious origin. My oldest Lexus in circa 95 and only replacement was needed on expected end of life and or wear. I have never regretted purchasing an OEM part. ymmv

Salim