How do you replace ignition coil on Lexus RX300?

Answer 1

Toyota/Lexus uses a direct mount ignition coil for each spark plug so you have six of them on your engine. If you have a bad coil the engine will run rough, the vehicle will shake, and your check engine light may light. The trick is to find which coil is bad. You may be able to get a free scan at a local auto parts store(AutoZone does it, maybe others) that should tell you which cylinder is misfiring. The cylinders are numbered like this as you look at the front of the vehicle 1 3 5

2 4 6

2,4 and 6 are easy to change since they are in front. Remove the vanity engine cover by unscrewing the L emblem on top of the engine and remove 3 allen (4 mm or 5/32) screws at the top front of the cover. You can then see the 3 front coils. Disconnect the wiring connector by pushing on the clip that holds it in place and wiggle and pull, don't pull on the wires though. Remove the 10 mm bolt that holds the coil down and then twist and pull the coil off the spark plug. I have seen cracks and arc tracks on the shaft of a bad coil but just because there are cracks doesn't mean it's bad. I have switched a suspected bad coil to a different cylinder and rescanned to verify that the code changed to that cylinder. 1,3 and 5 are much more difficult to get to but can be done by removing a couple small parts to allow

access. There is a good procedure on Lexus club forums called DIY Spark Plugs (if you have the patience). Try searching on Google for it. The individual coils run $80- 100 at stores, slightly cheaper online. On Amazon I saw a set of 6 for around $225.