hello again i looked good after more reading in this wonderful forum i had a disconnected hose behind air box .Thank you

So, I too am going through this situation. PO171 code with my recently purchased 2000 RX300 with only 67,000 miles on it. I've cleaned the MAF twice this latest time with a q-tip. I reset the CEL and everything is good, but then after a week of driving the light came on again with 171. Power seems to be fine, then again I don't know since I just bought the car a few months ago. Not losing mileage either. My next step is to check for vacuum leaks. Also have an aftermarket MAF sensor coming. Fingers crossed...

I had P0171 and tried cleaning the MAF without success. Replaced it and all is fine. They do go bad. Very common. cleaning is the first step but it doesn't always work.

Man, installed the new MAF sensor and the Check Engine light came back on again after about 100 miles of driving, then it went off again without resetting then this afternoon the error came back again. Is there a DIY vacuum test post somewhere? I just need to know where the vacuum is located so I can spray some brake cleaner. Thanks.

Is the brake cleaner safe to be introduced in the vacuum line?

Salim

Gas Cap defective.

Saw it on a few forums and videos online that used the brake cleaner. Supposedly the idle will go down if there is a leak.

Going to replace the air filter with an OEM one. I noticed the light after my wife went to Walmart for an oil change. She mentioned they changed the air filter. If that doesn't work I'll change the gas cap.

BTW, the light seems to come on when I am accelerating on the freeway.

Oh, I checked the often mentioned hose that's behind the MAF and it's connected.

That would be carb-cleaner and not the brake cleaner. Depending on where you squirt it, make sure it is safe for sensor. With carb cleaner, the rpm will go up.

Salim

Check the vac pipe is connected to the air box. It can get dislodged when the box is messed with.

Salim

Thanks Salim. I did check the vac pipe and it is connected. Going down the list of checks...

Just a note, my air box is not tightly sealed, only used zip ties. The oil change dude lost two clips for the air box, so I had to improvise. Can't just buy the clips, have to buy the entire air box assembly for several hundred dollars. CEL and VSC light would come on occasionally with air box intact, seems to come on less now with zipped tied, leaky air box. So air filter and air box is not a fix. I have had best results with just re tightening the gas cap. Car runs no different with lighs on or off.

If the end objective is the car that runs, you are OK. But the electronics in the car are observing an out of range value from a sensor or two and making its best effort to compensate for it and throwing out a code. In the county I live in, we are required to pass an emission test and typically you fail with CEL on. And parts, labor (DIY --> my time) will not get any cheaper over time, so I would do all I could to solve the problem. Or keep at it.

Vacuum leaks are hard to trace. A fiend of mine had a leak in a bellow-like hose. At idle there would be no leak and when you gas the engine, it would torque of the mounts and open up the bellow to let in air. Try the carb-cleaner.

Salim

I just had a code 0442 and read the posts, checked the little hose, seemed half way on, took off the neg. on the battery, put it back on and the code is gone....I have driven it around the neighborhood and turned it on and off a few times stopping in on other neighbors...I wonder if it is fixed? I will post the outcome.....


Wife called while out and said the check engine light is back on...

Hmmm,

the code definition says gas cap , so I replaced it.....shall see if that code rears it'ds ugly head again.

After several weekes with code P0442 & P0446, I just discovered that the hose behind the airbox was disconnected. My hands are too big to reach in there as is. Can someone explain what the best way to reach and reconnect the hose is?