2010 MAP sensor Mystery - P0108

There is a recall for the headlamp wires.
You should have cleaned it first. Several people have reported it was dirty, and it worked after cleaning.

 

mmm? I believe I miswrote. I was thinking the flow sensor...

 

Welcome to Prius Chat .

Some questions:

• Did you look for wiring damage when replacing the MAP sensor?
• Where was the sensor you were replacing located (the MAP is located by the throttle body)?
• Any accident damage or recent work performed?
• How long have you owned your Prius?
• Does your car consume oil?
• Any blockage around the inlet of the sensor to the manifold?

Good luck and keep us posted .

 

One way to check for sensor output is Techstream.

When you inserted the new sensor, did you disconnect the 12v battery to reset the codes, or reset them with a code reader?

To check the wiring, look at where the sensor connects to the wiring harness and follow it back as far as you can. Also check the fuse box and ensure alll fuses are good.

To gain access to the inlet area, pull the MAP sensor out and woth a small screwdriver, poke around a bit into the opening and see if there is some restriction.

Good luck and keep us posted .

 

How did you find the break? Thanks for sharing. My 2010 is doing the same thing.

 

I don’t want to make anybody feel put down, please understand that I only want to help. But...

These error codes frequently report that the MAF, MAP or O2 sensor is reporting bad data, but that doesn’t mean the sensor is bad! In this thread, it was the wiring leading to the sensor, but often, it’s another condition, such as a vacuum leak, which causes the sensors to report out-of-range data.

If someone has the same code as you, and doing X fixes the problem, that doesn’t mean it will fix it in your car.

The purpose of these sensors is to measure air and fuel flow, not to report whether they’re working or not.

 

@Bookkeeper, could you elaborate where you found the chewed open ground lead to the sensor? I have the same problem on my 2010. I get P0108 on my OBDII tester after replacing the sensor with a new one.

There's a bit of oil in the sump below the sensor, but not enough to interfere with its operation. About 2k miles ago I cleared out the EGR loop including replacing the blasted water-cooled EGR heat exchanger. What a job!

Can anyone post information that identifies the sensor's pin-out, showing the ground lead?

Thanks in advance from Indianapolis.

 

While you're looking for the right resources (the wiring diagram and the troubleshooting steps in the repair manual, both available as described here), I would recommend using them in a broader way.

Focusing on where Bookkeeper found a chewed ground lead would be prematurely narrowing your search to the exact wire that got chewed on in Bookkeeper's car in Pennsylvania 3½ years ago.

You'd be better off to simply start with what P0108 means ("The output voltage from the manifold absolute pressure sensor more than 4.5 V for 0.5 seconds. (1 trip detection logic)"), and use the wiring diagram and your multimeter and problem-tracing skills to pin down why that happened in your car.



That way, if you won the weird-coincidence lottery and your problem is exactly the same wire damage as Bookkeeper had, then you find it, and in the more likely case that something a little different is what happened in your car, you still find it anyway.

 

Thanks for the help, Chapman. Nice clear wiring diagram as if you drew it your yourself using Altium Designer or OrCAD schematic capture.

By the time I posted this question earlier today I had searched the internet for the MAP sensor's pin-out. A set of really nice color schematics kept popping up (likely pirated from Toyota's electrical manual) but I could not find the MAP sensor in its 600 pages. Then I realized that the manual refers to this sensor as a fuel vacuum sensor rather than MAP.

But it turns out that the schematic was unnecessary, though I'm very grateful for yours. The culprit was indeed a rodent shortening his teeth on my MAP sensor's wiring harness. I did a nice mid-span splice in the black ground wire using a soldering iron and heat shrink tubing, and the CEL is now off.

The chewed spot was about 6" upstream from the sensor's plug.

Thanks again to both of you for your help.

 

Thanks; I didn't draw that, I screen-grabbed it straight out of the Repair Manual.

When you're troubleshooting such things, you get to decide whether you're going to look in the Repair Manual first, or the Electrical Wiring Diagram (EWD) manual first.

The Repair Manual will usually have a little schematic of the circuit in question, like what I copied above. It will show you the connector callouts and the pin numbers, but usually not the wire colors. It is mostly for getting a high-level understanding of what circuit you're looking at.



If instead you head for the EWD first, in there you find the rest of the details, including the wire colors, any intermediate connectors and junctions (in this case there aren't any) and so on. That can all be helpful when you are ready to start poking at things.



But the Repair Manual is usually my first visit, because the diagram there is going to be part of several pages of troubleshooting information headed under the trouble code you got, which will tell you exactly what the code means, what the system does, and ideas for troubleshooting it.

Sometimes it can slow you down a little if you think you are looking for "MAP sensor" and the EWD happens to translate it as "E.F.I. Vacuum Sensor". Here is a post with some tips on finding your way around in the EWD more easily.

I notice in passing that if the black wire is the one you repaired, that wasn't the ground, that was PIM (the sensor signal).

 

i have the same problem but my code is P0107 couldn’t put the finger on the problem if you have any idea it would help

 

Another thread might have been better; a discussion of your P0107 problem won't be that useful to other readers looking at a thread about P0108.

But there is some basic advice that would apply just as well to a different code. There are explanations and troubleshooting steps for each trouble code in the repair manual:

Toyota Service Information and Where To Find It | PriusChat

You can see examples in this thread of how that information was helpful to find the problem. You would troubleshoot the same way, except of course you would turn to the section for the different code that you have.