My girlfriend's 2010 Honda Odyssey is throwing codes p0171 and p0174. That means it is lean on both banks.

It threw p0171 about a year ago and mechanic buddy of mine replaced the MAF sensor and the plastic intake boot. That seemed to fix the problem.

I checked the MAP sensor and at idle it was reading .9 volts when revved to 2.5k rpm the voltage dropped to .6 volts. I only found one source that says the voltage should increase to 1.4 volts but I wanted to confirm that before replacing a sensor I can't return.

I can't find a Factory service manual or any other site I trust with what the voltage should be on the sensors.

I appreciate any help in advance.

Thanks,

JD

I don't know the specific voltage you are looking for. In my experience I wouldn't suspect the MAP, you could see what the voltage was in freeze frame when the code set.

There may be a TSB on those codes for replace girlfriend with known good.
That being said, read no more below if you are looking for just the voltage.
Unplug the MAP, does it set a code? If it does it's passing KOEO diagnostics.
The codes are for both banks lean, need to check fuel pressure.
In freeze frame, are the 02/AF sensors reading similar?
What is LTFT on both banks in freeze frame? Are they adding fuel.
It's very possible if it has an aftermarket MAF sensor, it failed, need to test that.
You are leaning out both banks, Fuel pressure or MAF.

I'm confused about which sensor you are talking about and how you are coming up with these values.

quote:

I checked the MAP sensor and at idle it was reading .9 volts when revved to 2.5k rpm the voltage dropped to .6 volts.

MAP or MAF? I'd expect a 2010 to just have the MAF. Regardless, that isn't right for either of them. MAP increases when the engine is accelerated. The voltage range given for the MAF - ~0.9V at idle, increasing to ~1.4V @ 2500 rpm - sounds about right. It should not decrease as you are stating it does.

I'm going to assume this uses the MAF and the .9V decreasing to .6V is the actual value. Look at the sensor and see if any kind of foreign object is stuck in it, and if any is found, check the air filter/air box sealing. In my former career I have seen leaves, twigs and even a dead spider, as well as a total MAF failure due to the air filter missing. I further assume you've checked for vacuum or unmetered air leaks and low fuel pressure, also major causes of lean codes.

It has both MAP and MAF, in this case the MAP is used for EVAP leak monitoring (mostly).

Unfortunately I am but a humble public servant thst likes to pretend he is a mechanic. I don't even have a code reader much less one that can read live data.

I was getting my voltage readings from back probing the sensors.

I did find a hole in a hose going from a port right behind the throttle body to an unknown se sor. I replaced the hose and cleaned the MAF.

My girlfriend left and said it got worse so I had to surrender to a real mechanic. Luckily I know a guy from high school that I trust.

But I tried

You pretty much need a computer (i.e., a scan tool) to diagnose another computer, as well as someone capable of interpreting what it's telling him.

She hasn't dropped it off with him yet. It is her only vehicle and still has to do life. She is making arrangements with her dad to get it dropped off.