TLDR; the P0108 code keeps going on an off despite a new OEM gas cap (77300-52040), a new chineseium MAP sensor, and a new OEM vacuum switching valve (25860-31060).

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So earlier this year I got P0108 after my first 4K mile trip. Replaced the MAP sensor with a chineseium one and the code went away. Fast forward to October or so and not only was P0108 back but P0455 and P0441 came with it. Replaced the fuel filler cap with an OEM one and that did nothing. Replaced the vacuum switching assembly with an OEM one and that cleared the P0455 and P0441 codes. Funny thing is since then the P0108 code comes on and off about daily. I'm at a loss on what could be causing it unless this chinese MAP sensor is faulty--which I understand could be the case. The connector and harness connected to the MAP sensor look good.

Anything else to check? Should I clean out the rubber vacuum hoses? Clean intake?

 

The service manual lists this as a trouble are for that code:



The SM walks through a procedure to check the MAP sensor as well.

 

 

Doubt it's ECM so I'm back to square one with needing a new MAP sensor I'm willing to guess.

My ODBII tester does have logging and real-time data display so I can chevmyhe pressure and I believe voltage. Don't have much in a way to do the rest of that and I hesitate to take it to my local Toyota dealer to here in north Idaho Donne I have zero experience or trust with them. I may check with some other GX owners near me to see if they have a better tester and can assist.

 

See if you can find someone with a Techstream setup

 

Yup, that's my goal. Doesn't help that it's winter up here at the 49th parallel. LOL

 

why cant you use a voltmeter?

 

I could but a data logger would be more beneficial I think. I plan on testing the MAP sensor this next week when I have time to mess with it.

 

yeah a data logging voltmeter could be better.
what is really important is which end of the threshold you are passing.
if its the zero side then you could have a wire or connector issue. can just run it without any voltmeter and wiggle wires around.
majority of electronic issues are actually the connections. connectors, wires themselves and solder joints are the top 3 of that majority

 

I wouldn't be surprised if the pins on the MAP sensor are bad and or have broken solder.