I tried an experiment yesterday with my scan gauge 2. I disconnected the intake air temp sensor and MAP sensor, to see how accurate the scan gauge would be at retrieving codes. I got P0108 for the MAP sensor (high voltage) and P01113 (High Voltage) for the IAT sensor. The Scan Gauge easily cleared these codes when I turned off the engine and reconnected the sensors. It couldn't clear the codes with the sensors connected and the engine running (probably normal). Had this been a real situation, I would have known where to look. Also I would have saved a trip to the dealer (van still under warranty) or mechanic ($50). In a real world situation I would have avoided being taken by a sneaky mechanic. This may be a way to find a trustworthy mechanic. Disconnect a sensor, then reconnect it, not enough to make contact, get the check engine light to come on, retrieve the code, remove the scan gauge, take the vehicle to the mechanic, and see what he/she has to say. If he/she gives you a diagnostic that is way off/expensive, then you pay the fee and go to the next. This can be an expensive experiment, but I believe it will save you money in the end. Just my 2 cents and another reason to take the plunge and buy a scan gauge 2.

that is good to know. just hide the scan gauge or they might suspect something.

Yeah I really haven't looked for a mechanic yet because my van is still under warranty. I think the government should mandate a trip computer that displays MPG. I think most people would change their driving habits. I'm not sure if my experiment would be ethical or not, but sometimes money and ethics should be seperated completely.

I also noticed in the listing of things that the scangauge will do, that it will keep track of the top speed for your trip, so if you have a teenager who uses your car (bad idea for every reason) you can keep track of their to speed, and of course if you keep it on the dash, you can quiz them as to why they got poor mileage, or whatever as well.

Hello -

Great way to identify the trustworthy mechanics!

CarloSW2

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One should be careful not to take the trouble codes too literally however. A perfect example of that would be a code for high coolant temperature concurrent with low intake temperature.

First person with the right answer on where to look first wins a donut.

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I think, therefore I doubt.

Snax I was suggesting finding a trustworthy mechanic using the scan gauge as a reference. For example you disconnect the IAT sensor, get the check engine light, and take the vehicle to the mechanic. If the mechanic says your check engine light is on because something major is wrong, then obviously he's jipping you. His first job should be to check the IAT sensor. Get where I'm going with this?

Mmmm. No idea, but, on some cars, the coolant flows through the intake in order to warm up the incoming air. If the coolant was low (due to a leak), the intake would be cooler while the coolant (what was left) would be hotter.

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My vacuum tube was disconnected inadvertantly, but 2 different people read the OBDII readout as a bad O2 sensor. Maybe that's just the reader, not the mechanic.

Matt actually diagnosed it after reading a description of what was going on. But a buddy who lives here locally actually spotted it and reconnected it for me.

I really need to learn how to do more stuff on my own.

m