Fixing P0300, P0301, P0302 with MAP Swapout

Huh...I JUST cleaned my MAP sensor and it doesn't have that red bit. And I've had no issues. Looking at pictures online, it doesn't look like the oem part has that red part.

Did you buy your part from toyota directly?

 

I'm glad you resolved your problem.
That "red" thing is the sensor.

 

Have you cleaned the EGR components, and the intake manifold?

 

I noticed on our 2012 that the MAP sensor looked different from the 2010. I was afraid I had broken off the sensor wire on the 2012. But I think Toyota actually changed the design so the later ones don't have the exposed wire, or something...

 

Hmm, 2010 shows two different MAP part numbers; the -52010 one is $34 more than the -47010 one.


ELECTRONIC FUEL INJECTION SYSTEM. 2010 Toyota Prius | Toyota


Google image search for the two part numbers mostly seems to show the -52010 having the extra doodad, and the -47010 without it. Whatever it is, I guess it'll cost ya an extra $34.

8942147010 - Google Search

8942152010 - Google Search

From memory, I think the one in my 2010 is doodad-negative, but it's been a while since I looked.

I'm guessing the doodad is not the absolute-pressure sensor itself (since the versions without the doodad presumably still sense that); it might be an additional sensor of some kind, like the way the MAF sensor also has the intake air temperature bulb sticking out of it.

The additional sensor might be to compensate the reading for something.

As both show up for a 2010, it may be VIN-specific which one that car's ECM is expecting to see.

I wonder whether @Elektroingenieur has any inside info about this.

 

Interesting. I thought maybe they were trying to pull the sensor wire further out of the path of the inevitable puddle in the throttle body.

I'm wondering for OP's case though if there could have been a decent way to test the sensor, since they aren't cheap enough to swap willy nilly and there are so many other possible causes of misfires to chase. For my "broken wire" I just looked at some OBD2 readings and figured "looks about right". But the OP one's failure mode might be less obvious than that.

 

The information is omitted from the version on parts.toyota.com, but the Electronic Parts Catalog shows that 89421-52010 is used on third-generation Prius cars made from April through October 2009, and 89421-47010 is used on such cars made in November 2009 and later. Neither part is listed as a substitute for the other, and both are also used on other Toyota models.

I couldn’t say how the parts differ or why the change was made.

 

Stick it in a mason jar where you've made holes in the lid for the wires and a vacuum nipple, goop up the hole where the wires come through, supply 5 volts to the sensor, use a vacuum pump to lower the jar pressure and see what voltage you get back.



There is a pullup resistor in the ECM (the repair manual diagram shows it, but doesn't show the value), so depending on how the sensor's built, your voltage in a test jig might not match the above exactly, unless you've used the right pullup value. Or you could just take the mason jar out to the car and run the regular wiring harness into it, then ask the ECM what pressure it's reading.

 

Why is this thing so expensive anyway? Honda MAP sensors are less than a hundred.

 

Because it can be, I’m afraid.

In Japan, the Toyota list price for either part is ¥5,400, or about $50 (U.S.) at today’s interbank rate. If you don’t need one right away, there would be a substantial savings by buying from an exporter; the cost of international shipping for such a small part would be much less than the U.S. distributor and dealer markup.

 

Our 2010 MAP sensor has that little “resistor” thing, can’t recall the colour. BUT, I dropped in on a local Priuschatter who was doing his EGR, and his was missing the resistor bit.

at the time I speculated his was broken, but later I googled images and did see a lot without that bit.

ours is 2010 model year, and IIRC his was 2012.

 

If I'm reading #8 right, it seems like certain early-production 2010s should be doodad-positive, while later 2010s and all later-year Gen 3s should be doodad-negative.

 

Sounds like you walked through hell on that one! Glad you shared it here, maybe we can find an easy enough way to save the next poor soul a few blisters or $$....

I like @ChapmanF 's mason jar bench-test idea, but I think most of us DIYers wouldn't muster the gumption to try it. I also like the idea of using the ECM for the data reading. I know we can look at this using Torque or Techstream, the only missing thing is recognizing good sensor data from typically bad.

This 1A Auto blog post How to Test a MAP Sensor describes using a scan tool to graph MAP and doing a few checks. Apparently one of the failure modes is intermittent output, which will look spiky.

So I did a quick-and-dirty test with Torque. I used the Graphing tool and selected only "Barometric pressure" and "Intake Manifold Pressure" -- both generic PIDs (i.e. not the special Prius-specific extended PIDs that are also available). The graph output shows that with the ICE off, as expected the MAP and Barometer read nearly the same, and then when you kick the ICE on and ramp up the gas you can see the vacuum changing sort of smoothly.


That one spike is my foot hesitating as it forces the ICE on while in PARK.

Torque's graph tool only let me export as a screen shot, so I can't scroll over to show what driving around the block looked like. (I also really hate that there are no units on the graph.) If I had used Torque's data logging feature (instead of Graph tool) it would have exported a .csv. I apologize for the low-effort. Not sure we'd really learn much more from that anyway.

Maybe at some point we'll get to see what a real live bad sensor looks like for comparison. Obviously a dead one wouldn't change much or match the barometer, and a jankier output would be the intermittent failure mode.

 

I replaced the 2010 Prius MAP sensor with a much less expensive aftermarket MAP sensor listed as compatible and it has been operating fine for the last few months.

SM-G960U ?