99 AWD Rx300 Check engine light problem. - Toyota Nation Forum : Toyota Car and Truck Forums

Christian87N · 10-04-2005, 01:55 AM

Hey guys,

Just recently my check engine came on for a couple of days, and it shut off yesterday. The rex has been doing good and i havent felt anything different. I'm going to the dealership on Friday to get a diagnostics check to see what the problem was. Im thinking that it might have been the quality of the gasoline....

My question is....what would make the check engine light come online for a few days and then go offline out of no where?

Thanks in advance for any input on this.

bj300 · 10-13-2005, 09:53 PM

I had the same problem for a while - the light would come on for a couple of days then disappear. Unfortunately after awhile it did not disappear. I had been told the problem was an air flow sensor. Taking it to the dealer tomorrow. I believe they quoted around $350. That was over a month ago.

I have a cousin who had the same problem with the check engine light. I haven't notice or heard any strange noises in my car, but she eventually had problems.

Are you aware of others with the same problem?

lextech · 10-14-2005, 06:41 PM

well could be multiple things but most of the time when the air flow meter is dirty if u excell hard or quick u will hear a poping noise in the air box then as it gets worse the car could stall yata yata but probobly emissions code

lexusmech · 10-14-2005, 11:23 PM

Two things, like they said, MAF or loose gas cap, I see them both....A LOT. On the MAF, remove it (two screws and a connector, it's on top of the air box with a 6? wire connector). Flip it over and you'll see a wire with a glob of epoxy on it. Also look DEEEEP inside and you'll see a little thing like an electronic resistor. Using a Q tip, gently clean the gunk off both of these item. Also using brake clean from the auto parts store might help. Not saying it's for sure but it might save you $350.

If it's the gas cap, go get a new gasket from the dealer and change the rubber o ring on the gas cap and be sure to tighten it several clicks. The gas tank/evap system starts from a cold start and measures several things like vacuum from the gas tank. If the tank leaks twice in a row, it will trip the light. Thank the ECO warriors for that one.