2008 prius mass air flow sensor problem

It is common for them to get dirty, uncommon for actual need of replacement. Did you use CRC Mass Air Flow Sensor cleaner? Carb/throttle body cleaner will make it very unhappy.

Replacement is very simple, FYI. To reset the check engine light, disconnect the battery negative cable for 5 minutes.

 

It would be a rough start for starters,just clear the CEL and see if it reappears.....be sure to let us know!!

 

Are you running an aftermarket non-paper air filter, by any chance?

 

It should be covered. Perchance, did this problem occur shortly after a service that was performed by your Toyota dealer?

 

Reseat the MAF connector below the air throat. I recently started a thread on the subject. Check andyprius threads. :cheer2:

 

@seilerts @cwerdna @andyprius Thank you so much for your posts above.

I just drove from Atlanta to Nashville, and on a long uphill part of the freeway, the Check Engine Light came on.

When I arrived in Nashville, I immediately went to AutoZone to get the diagnostic code read.

I'll attach the printout here, which says "P0101 Mass or Volume Air Flow Circuit Range/Performance. Most likely solution: Replace Mass Air Flow (MAF) Sensor".

Then, the Check Engine Light eventually turned off while I was driving around Nashville the next day. But then it came back on on the third day, and it's still on now (after my long drive back to Atlanta).

I just removed my MAF Sensor to inspect it, and I'll attach photos.

Based on what you wrote above, it sounds like you think "Replace Mass Air Flow (MAF) Sensor" would be overkill and that I ought to just use a cleaning spray as shown at

and

Is that true?

By the way, https://amzn.to/3jshnsc is the replacement engine air filter we installed Nov 2019.

Thanks, everyone, for your help!

 

Absolutely clean your MAF. Very common problem on many Toyotas. Often sets P0171 code. In particular your third picture, the passage up from the side of the sensor. There are two "resistors" up in there that do the actual sensing of airflow- they should be kind of shiny gray-white. Normal use eventually covers them with black goo.
Use MAF cleaner spray. If you are very careful you can soak a "fuzzy craft stick" (aka a pipe cleaner) in the spray and GENTLY rub the sensing elements- they are fragile!
Should look like this.
You can clean the bulb that's out in the open as well- that's an air temperature sensor.
Posted via the PriusChat mobile app.

 

@mr_guy_mann Thank you so much for your helpful response and photo! I will probably be able to buy the spray today, and I don't have a "fuzzy craft stick" but might try a Q-tip cotton swab if the spray doesn't fully clean those 2 inner sensors.

 

Officially, Toyota seems very down on touching the sensor elements with anything, other than the stream of sprayed MAF cleaner itself.

 

I used https://www.napaonline.com/en/p/CRC05110 Mass Air Flow Sensor Cleaner (which I bought online, and then somehow it was delivered to my front door within a couple hours for FREE, which was a pleasant surprise), and then after cleaning the sensors (without using a cotton swab or anything else—just the spray) the CEL was still on for the first drive but had turned off by the next drive. Maybe it will remain off!

 

I would not use q-tips. The sensing elements are easily damaged and a cotton swab doesn't have much "give". If you don't have pipe cleaners, then just spray it and see how it looks.

Posted via the PriusChat mobile app.

 

That reminds me of a digital camera sensor cleaning tip: half-break the stalk of a Q-tip, so that it has a lot of give, will only lightly ride on a surface.

I took a look at ours once; it looked pristine. It's downstream of the air filter, wonder how it would get dirty: less-than-tight air duct connections?

 

Hello I have a 2009 touring prius that I took to toyota for oil change. When I got car back engine light was on. They took it back in to reset it but when they came out the hybrid battery light was on. Technician told me I could drive it like that but the hybrid battery was not going to work. They took it back inside and they replace mass air flow sensor but this time car would not start. They said sensor was good. However, They said there was a problem with the harness where mass flow sensor its connected cause everything they would mess with harness it will pull up different codes and mess up the car?? Car was not starting at some point so they reseted car again and car it's been runnimg smooth like always. Guy said its probably electrical