P0101 and also Flickering Headlight

Hello all,

I have a P0101 code and a flickering right headlight on my 2008 Prius. I've been trying a few steps to resolve those issues, but wanted to check in here to get some input, especially about the P0101.

The car has had a replacement (non-oem) catalytic converter for a few years and an 02 sensor spacer that I installed because I was getting P0140 codes.

I would be grateful for input.

• P0101 / MAF code.
  • I replaced the sensor with a cheap generic sensor from eBay
  • I replaced the 90 degree 02 sensor spacer and also the 02 sensor itself, thinking that maybe these were somehow causing the P0101.
  • Considering cleaning the oem Denso MAF sensor and reinstalling it as a next step.
  • I verified that there are no cracks in the big plastic/rubber hose and that it's securely attached.
  • Car has a new air filter and cabin air filter, and I verified that engine air filter is securely installed, rubber seal is fitted well.
• Flickering headlight
  • Right headlight only.
  • I replaced the battery a couple days ago at autozone and noticed that voltage is a bit lower than the 12.6 idle/11.5 loaded range that I'm seeing listed around the internet as a good range.
  • I can't remember exactly what the range was on my car's diagnostic display, but maybe 11.2 and 12.0 or something like that?
  • The car is frequently starting with the issue where the dash lights don't come on, and the right headlight doesn't come on until I restart the lights a few times.
  • When it does come on it flickers, at least until the car has been running for a bit.
  • Would all this maybe be because the battery was sitting on the shelf for awhile and needs a long drive to get up to full charge?
  • More likely an issue with the headlight itself? Or both perhaps?
  • The headlights are generally dim, although I don't know if this is just a limitation of the lights or if it's an indicator of an issue with the electrical system/battery.

I would be grateful for suggestions on next steps with either or both of these issues.

Thanks all!

 

Thanks MAX2, I'll try cleaning the Denso (original/OEM) sensor and reinstalling it and then seeing if that clears the code.

Still open to other ideas and suggestions as well if anyone else has thoughts either on the battery/flickering headlight, or whatever else, thanks!

 

Thanks all for your replies! Still troubleshooting. After getting a new battery and going on a roadtrip (several hours each way), the voltage is at 11.6 loaded (lights on) and 12.2 with lights off on the diagnostic display. After spraying about half a can of MAF cleaner onto the original Denso MAF sensor and reinstalling it, the check engine light did not come on for about 150-200 miles and then it came back on. Then it went off again after 150 miles and stayed off for another 200 miles and came back on again.

As a next step, considering that the voltage seems a bit on the low side (?) I am thinking that I might try exchanging the battery at AutoZone, based on the thought that maybe it had been sitting for awhile and that it had lost power while on the shelf or something?

For the MAF, I am thinking I could try finding some Denso sensors at a junk yard as one commenter suggested and then also cleaning the throttle body as another commenter suggested, and just keep chipping away at things.

The dash lights routinely don't come on and so I've been using the method of opening the door, pushing power without the brake pedal engaged, turning on the lights, and then completing the start-up process, which usually seems to bring them back on again.

I'll share updates if I get some of these issues figured out, thanks all.

 

Thanks dolj for the tip about the capacitor, that makes a lot of sense because it has become almost constantly necessary to go through that intermediate step in order to start the dash lights. I've become fairly good at it at this point in terms of being able to go through the sequence on successfully on the first try 90% of the time now, but I grasp the concept that each start still requires more power than a typical start should in order to go through that intermediate step.

MAX2, I was measuring voltage with the car off -- i.e. push start button twice without holding the brake pedal, then go into diagnostic mode and look at voltages on the display with lights off, and again with lights on. I have not yet measured voltages with the car running.

I'll look into repairing or swapping out the Combination Meter, likely through the swap out approach with Texas Hybrid Batteries, or maybe see if there's a local repair person who might be able to do it in my city for a reasonable fee.

This is a big step tho in terms of chasing down (at least on of) the problem(s).

I'll share updates about how things go as time goes on, might take some time to get any more work done since the next step would require ordering parts or scheduling a repair (I'm not really eager to take on an electronics repair job DIY) but I'll update after things progress etc.

Thanks All!

 

Update on the thread...I found a technician to replace the capacitor on the combination meter (thank God) and it seems to be working fine, have not experienced any issues with the dash lights for several days. Still having odd electrical issues with the car pretty much every time I drive, whether it's flickering headlights or today, had a clicking noise and rear brake lights and front turn signals flashing on and off issue along with display lights flashing on and off all at the same time in sync with the clicking noise.

I did go to the diagnostic display while the car was running and found that the voltage was alternating between 13.9 and 14.0 while the car is running.

I do suspect the battery because, although I've seen some of this kind of stuff in the past (e.g. the occasional headlight flicker, the occasional clicking noise with a low battery) a lot of the issues started when I replaced the battery a couple of weeks ago.

I've noticed that headlights will routinely lose power while driving -- one or the other of them will turn off and then I'll have to switch the lights off and back on and then they'll both come back on.

Thinking a next step might be to return the battery to autozone and (1) verify that I got a compatible battery and (2) install a new battery that hopefully isn't defective/depleted etc.?

Also, random side question...would it be a good idea for me to replace the headlights with LED lights or something instead of HID lights which another commenter mentioned is probably what I have?

Will keep folks posted on how it all goes and feel free to share any other ideas if you have them, thanks all.

 

Thank you dolj, I appreciate your help in narrowing down the issue with the headlights, I'll replace the HID bulbs and ballasts.

Any idea what might be causing the other electrical issues -- clicking, lights blinking on and off etc? I did notice that these became more frequent after replacing the 12v battery a couple of weeks ago. Beyond that I don't really have any ideas, and learning about things like the CM issue are definitely why I come here!

 

I resolved those issues (clicking/blinking lights) by disconnecting the 12v and reconnecting it to reset everything. So...maybe also possible(?) that one of the connections on the battery was just loose or something? Not sure on that one but throwing it out there as a possibility. Thanks all for your ideas here with troubleshooting!

 

Thanks dolj -- quick update, I got around to reconnecting the red/positive 12v battery cable and that seems to have made a difference: no clicking noise or blinking issues in the car, so I think it was just loose after a rushed initial installation in the autozone parking lot at closing time.

Still need to solve the issue with the flickering headlights. I watched some youtube videos about replacing the ballast and that looks like a pita so I'm going to try swapping in some LED bulbs.

No more issues with the dash lights in the past couple of weeks, and the check engine light/P0101 code has not made an appearance during that time either, so will keep my fingers crossed on that front as well but if it reappears then I'll proceed with further cleaning steps that mr_guy_mann suggested.

I ordered some LED bulbs from eBay and some butt end connectors and a crimping tool, and going to give the LED conversion a shot.

I'll share an update after that job, but it may be a bit before I get to it.