I'm not an expert at diagnosing codes, but, in general, 0303 is for a misfire or timing error in the cylinders. 2237 is for the oxygen sensor. The first thing to check whenever the engine light comes on is a loose or worn-out gas cap. It has to form a tight seal, or else it, too, will trigger the light. That's to keep gas fumes in the tank and filler-pipe from leaking out into the air.

If they have replaced those parts (or gone through the proper diagnostic procedure for those codes, which requires a Shop Manual step-procedure, not just a knee-jerk reaction replacing parts) and the light still keeps coming on, you may (?) need a new engine-computer.

 

P0303 is Cylinder 3 misfire. If the plugs have been changed then it might be a bad ignition coil. You can always test this by taking and swapping it out with another cylinder and seeing if the misfire moves to that cylinder. If you need a coil go with the Denso Brand and you can find them cheap at Rockauto.com. They are extremely easy to change out and you can do this yourself in about 2 minutes.

P02237 suggest you have a problem with Oxygen Sensor Bank 1 Sensor 1. This can also be replaced in about 5 -10 minutes. When ever replacing Oxygen Sensors use the Original Equipment Part (Denso). You can always get them at Rockauto.com for a lot less.


Get one of these if you plan on keepign the vehicle for a while


Also get this scanner



Watch a few Youtube videos, there are plenty of guides on this board and go to HarborFreight and get a cheap socket set and some wrenches and do it yourself. Stop paying people to fix the easy stuff.

 

 

 

Here is a tip when trying to find info. Do a search in google and typically it will bring up the club lexus link. It works better than the search function on this site (I think).

https://www.clublexus.com/forums/is-...ensor-1-a.html

It is the sensor in the engine compartment that is located in the exhaust manifold on the passenger side. You will need a special socket typically and a ratchet. They don't cost very much.

https://www.harborfreight.com/78-in-...ket-69022.html

Switching out the coil with a different coil from another sensor should tell you if the coil on Cylinder 3 is bad because the cylinder you move it to should throw an error code. You just need a small socket and a ratchet to remove it (very easy). Cylinder 3 is the middle cylinder in the passenger side (1,3,5) with cylinder 1 at the front. So swap 1 and 3 and see if the error code moves.

Now if the error code doesn't move and you still get the same error code on cylinder 3, you might want to pull the plug on cylinder 3 and take a look at it. If it looks fine maybe have a compression test done on cylinder 3 (it could be bad).

As a side note the Oxygen sensor on that side is throwing a code also. Try and fix the cylinder code first to see if the oxygen sensor code goes away.

 

I like this guy. That's a decent way of diagnosing this issue without the use of a Techstream. If your scanner or your mechanic's scanner has the ability to see freeze frame data you would be able to see the conditions under which the malfunction occurs... engine speed, vehicle speed, load, etc. Put the vehicle in CHECK MODE and drive it within those parameters and you'll arrive at your answer sooner than later.

 

 

Don't let the VSC Light distract you. It comes on no matter what code you have. It is a precaution the car takes and automatically disengages VSC. When you reset the code and clear the computer the car runs great because it is trying to relearn air/fuel/driving. It eventually throws the code again once it determines that something is wrong.

And yes, just undo the little bolt holding in coil 3 and switch it with cylinder 1/coil. You might want to clear the codes and then drive it and see if you still get the same code. Autozone should be able to clear the code for you or you can just unhook the neg battery cable for a few seconds (although you will lose your radio presets and have to reset your car windows).

Let us know what you find out.

 

Necroposter here, too. I also got the OP440 code and it turned out to be the 5/16" vacuum line with the green test port in the middle. I was in a hurry, so I just chopped out the port and put on some new line tonight. Disconnected the battery to reset the light and expect it won't come back on tomorrow.

I was putting off replacing all of the vacuum lines, but now will do everything this weekend. I just need to take a full inventory of line sizes and purchase the needed quantities. I did get what looked like some neat hose clamps with built in keys to tighten them, but the keys fell off after a few turns. Still need a flat blade screwdriver, as the Phillips head is too small for the screwdriver I had. Anyway, check your old hoses and replace them today!