CEL P0101 Mass Air Flow Sensor (1 Viewer)

[cc93cruiser]

Geez, just fixed my heat exchanger leak on my new to me 09 LX and all was good for about 2-3 weeks and now this.. Took a 200 mile round trip out to the coast with my family and all was good. On the way back home a got a CEL light along with the VSC light and the 4lo light flashing.. I was assuming that the rig was going into some type of limp mode, but nothing.. It drove flawlessly the remaining way home (approx 100 miles), just lights never turned off.. On way home while parked I thought I would give 4lo a try since the damn light kept flashing, but it was a no go... I am assuming this is the limp mode, no 4lo.. I finally got home and plugged in my trusty obd2 scanner and I came up with a single code, P0101-Mass or volume air flow range.. I am assuming the problem lies in the mass air flow sensor? I haven't erased the code from computer. I think I will start with taking air filter box out and intake tube and take a look at mass air sensor, maybe dirty? However, I do have a brand new air filter though... Any thoughts or advice or anyone have this same code come up/fix? I was hoping if everything looks good while inspecting air sensor, I will erase code and hopefully it was some type of computer glitch and truck will live happily ever after.. What you guys think? Here's a couple pics of instrument panel lights that lite up and the code from my obd 2 Torque App...

 

[cc93cruiser]

Oem Mass Air meter retails for south of 100 bucks, might just swap the bastard out... But is there any chance of cleaning the old one out?

 

[cc93cruiser]

Thought I had this beat, problem came back 2 weeks ago. Oem air filter and everything else checked out. Basically check engine comes on after like 300-500 miles of erasing code with my obd2 app. Truck runs perfect with or without the CEL on. Was wondering if anyone has had this issue with their 200. I am thinking bout just replacing the mass air flow sensor but I'm having doubts about the sensor being bad since the truck runs perfect either way.. Just don't want to buy this and then find out it didn't do anything to fix problem.. Any thoughts? Do these sensors go bad over a period of time and not right away, explaining why rig is still running fine?

 

[TonyP]

Pull the sensor and blast it with some MAF cleaner to see if that helps.

 

[Sandroad]

The sensor may be reading out of range, which would trigger a code, but if it's not way out the engine will run ok. When you use cleaner, use the real stuff and not just the leftover can of something you have on the shelf.......

https://www.amazon.com/CRC-05110-Ma...29&sr=1-1&keywords=mass+air+flow+cleaner&th=1

If cleaning doesn't do it, spring for a new one. And make sure your air filter airbox has a good seal and that the intake to the airbox is clear.

 

[Taco2Cruiser]

I might get heat for this, and I don’t like mentioning things that could waste money, but here’s my opinion.

Some years back when I got really crafty with replacing Toyota ECUs with my own, I found that the O2 and air/fuel sensors with over 100,000 miles would not read very accurately, yet they would never through a code on their own. I had the same issue as you once and chased it to the MAS, and found that that sensor also didn’t read very accurately past 100k. Now I’ll be there first to say, no, it’s not a priority, it’s just something I feel I like to do, escpecially beciae it only costs me about $250 and I do it every 10 years or so per vehicle.

Long story short, I’ve fixed a few other friends with your issue the same way. Not a ton, just a few, so take this with a grain of salt.

Either way, I replace my MAS, O2, and air/fuels with my spark plugs, at 120,000 mile intervals because of the benefits I’ve seen on my tuning PC.

 

[cc93cruiser]

Pull the sensor and blast it with some MAF cleaner to see if that helps.

The sensor may be reading out of range, which would trigger a code, but if it's not way out the engine will run ok. When you use cleaner, use the real stuff and not just the leftover can of something you have on the shelf.......

https://www.amazon.com/CRC-05110-Mass-Sensor-Cleaner/dp/B000J19XSA/ref=sr_1_1?s=automotive&ie=UTF8&qid=1514939329&sr=1-1&keywords=mass+air+flow+cleaner&th=1

If cleaning doesn't do it, spring for a new one. And make sure your air filter airbox has a good seal and that the intake to the airbox is clear.

Been there done that.. Bought the MAF cleaner and cleaned just about everything including sensor...Code still comes up...

 

[cc93cruiser]

I might get heat for this, and I don’t like mentioning things that could waste money, but here’s my opinion.

Some years back when I got really crafty with replacing Toyota ECUs with my own, I found that the O2 and air/fuel sensors with over 100,000 miles would not read very accurately, yet they would never through a code on their own. I had the same issue as you once and chased it to the MAS, and found that that sensor also didn’t read very accurately past 100k. Now I’ll be there first to say, no, it’s not a priority, it’s just something I feel I like to do, escpecially beciae it only costs me about $250 and I do it every 10 years or so per vehicle.

Long story short, I’ve fixed a few other friends with your issue the same way. Not a ton, just a few, so take this with a grain of salt.

Either way, I replace my MAS, O2, and air/fuels with my spark plugs, at 120,000 mile intervals because of the benefits I’ve seen on my tuning PC.

Will must likely go this route, minus the O2s.. Currently have 93k so was going to swap out spark plugs and MAF sensor.. I will also be replacing the pcv as that has never been replaced. IIRC I think I read somewhere that some tundra owners were having similar symptoms on their 5.7s with the original pcv valves...

 

[cc93cruiser]

*update*
Replaced the PCV Valve and no more P0101 code. It had never been replaced at now nearly 100k.

 

[LXinOBX]

Gents, just had the exact same thing happen ('10 LX - 135k) at about the 250 mile point on a 330 run we do pretty frequently in the summer BUT have not done since last fall.

Called dealer (excellent tech) and he thought I might have a fuel cap issue. Stopped at Advance Auto and pushed P0101. Dealer closed by time I pulled the code - not in until Mon.

Is the general consensus it is the PCV?

Truck runs fine - just not liking the dash "light show"

 

[cc93cruiser]

Gents, just had the exact same thing happen ('10 LX - 135k) at about the 250 mile point on a 330 run we do pretty frequently in the summer BUT have not done since last fall.

Called dealer (excellent tech) and he thought I might have a fuel cap issue. Stopped at Advance Auto and pushed P0101. Dealer closed by time I pulled the code - not in until Mon.

Is the general consensus it is the PCV?

Truck runs fine - just not liking the dash "light show"

same exact symptoms... I would swap the pcv valve it has never been done (mine was shot).. It literally is a 10 min job...Have over 2k miles since replacing valve, CEL never came back...

 

[cc93cruiser]

Btw, have you connected a obd2 scanner to it?

 

[LXinOBX]

Yep, same code (pulled into an Advance Auto and got P0101). AZ data base said mass flow? WTF? I mean how are they connected to the VSC and, even more random, 4WD Lo? Anyway, the guys allowed me to use their PC and google pulled up (of course, iH8mud) your post.

Did you have to reset or did your "lights" extinguish after driving a while - after replacing PCV?

Also, did you ever try cleaning the valve first (so the little ball moves freely?)

Sidebar - I've never, save an 40 series in the '70's, had to change a PCV

Thanks, cc93, appreciate the feed back (btw, was just in Hayward this past Weds!)

 

[mpho]

What is a PCV valve?

 

[LXinOBX]

As I recall - positive crankcase ventilation - so positive pressure gases in the valve cover can escape - allows vapor to only go one way. At least that's what I remember - it was , after all, 40 years ago....

 

[chilibit]

Oiled air filters, pick your poison, have a reputation for coating MAF sensors and of course disrupting the temperature drop so that it is out of tolerance. I tossed oiled filters for everything in my garage except carburetor motors. Yes, you can use a K&N but you have to be careful about the amount of oil. The OP did not mention what kind of air filter was employed.

 

[cc93cruiser]

Anyone know who is the oem supplier for toyota on the Mass Air Flow sensor on the 200 series? Took mine off and it says Hitachi Made in Japan...Wondering if this part had been replaced with an aftermarket unit or is this oem part...Hitachi part number MAF0103

 

[LXinOBX]

Just a quick follow on the above post - need to replace my MAF - is this "still" the one recommended by y'all?
Hitachi MAF0103

If not, please advise, if it IS correct, AMAZON is showing it at $63 - any other recommended sources?

Many, many thanks!

 

[cc93cruiser]

That is the correct oem unit..... Make sure you clean out your throttle body too with some cleaner....After replacing my mass air sensor, cel would still come on... After after busting out the FSM, I decided to check anything that might cause this issue (vacuum hoses/pcv etc) and cleaning the throttle body blade really well did the trick....