jvmagic Posted May 25, 2021 Share Posted May 25, 2021 Hi, My is250 has 110k miles and I've haven't performed a spark plug replacement etc (just basic maintenance throughout the years). The CEL came on yesterday with the P0303 code and the car ran real rough. After reading the code, I reset the computer via my handheld scanner. It's ran fine and no CEL after driving 10-15 minutes. Not sure if I should risk driving further. Any advice would greatly be appreciated. Thanks in advance Quote Link to comment Share on other sites More sharing options...
dcfish Posted May 25, 2021 Share Posted May 25, 2021 https://www.engine-codes.com/p0303.html That's all I have for now... Quote Link to comment Share on other sites More sharing options...
Cfauvel Posted July 5, 2021 Share Posted July 5, 2021 P0303 means a misfire on cyl 3. I'm new to any Lexus IS250, so you'll have to find a cylinder number diagram to find out which side and what location the #3 cyl is . The misfire can be a host of things, but a few of the usual suspects are Spark Plug (doubt it) Coil (most probable) Injector The easiest thing to do is to clear out the codes and move coil #2 to position #3 (and vice-versa) and see if the PO3xx moves to P0302....If it does that means the coil is bad. I highly recommend to getting an OEM coil or high-performance coil as some aftermarket coils jus don't cut it. Report back after that test. Quote Link to comment Share on other sites More sharing options...
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