2011 Prius MAF Wiring Problem

is the car running fine otherwise?

what wiring was altered and why?

i would check any connectors for looseness and corrosion

 

A mechanic who genuinely wanted to solve an issue like this would first look in the repair manual to see what the P0101 code means, and look at the eight pages of troubleshooting info there for ways to pin down the problem.

The code means that while the engine was running, and warmed up, and operating in a load range where the throttle position sensor voltage is from 0.2 to 2 volts, the ECM computed how hard the engine ought to be working based on the driving conditions (a), and also computed how hard the engine seems to be working according to the MAF reading (b), and divided b by a, and got a result below 0.829 or above 1.153. (If the two calculations of engine load perfectly matched, of course, the division result would be 1.0 exactly, so this means that for some reason the two ways of calculating the load on the engine are mismatching by more than 15% or so.) This has to be the case for more than 10 seconds and be noticed on two different trips.

Then the eight pages of troubleshooting have you look at all of the various reasons why that might be, so you eliminate the ones that don't explain your issue, and you end up knowing which one does, and then you fix that.

That involves thoroughly checking for vacuum leaks, EGR possibly stuck open, and so on.

The trouble is, a lot of shops employ people who will look at a description like that and say "Uhh. Yeah. Maybe the next customer needs a battery I can replace." And they'll tell you something like "that would have to be a loose wire that we'd have to fix for $3000" so you will go away, and they can replace somebody's battery.

Sometimes DIY becomes easier in a situation like that. Not just because it's often cheaper, but flat out because solving the problem is going to require somebody to go through the steps, and maybe the shop guys won't do it.

 

Searching for a loose wire, or bad wire, etc., is very time consuming. And a royal pain in the butt!
I've done stuff like that.
When you get a bill for 10 hours labor to fix a loose wire, you are not happy!

Have you tried taking it back to the place that modified the wiring???

 

Also, pretending it's a loose wire, to get out of trying to find the real reason the two computed engine loads aren't within 15% of each other, can turn a problem into a real pain in the butt!

 

Sorry, I must have misread it...