I need some more suggestions please. Had to change the Head gasket out on my 2012 prius(400000+miles) and since then have had the p0012 error code. Have changed the oil etc what seems like a billion times, sometimes with cleaners too. Have replaced all the potentially affected sensors out. Have replaced the timing chain(which was slightly stretched) and the vvt gears etc. Just had to replace out coils too as was getting misfire codes but that was just a recent thing. Engine runs "ok" and when I clear the dtc codes for the first drive it doesn't come back on but it always does on the second drive! Also most likely unrelated passenger airbag remains illuminated "off" even with passenger needing one sitting in seat? Any suggestions please
Yes ocv is changed. Now I m thinking to check oil pump pressure and same time rotate engine manually to see oil circulation inside head. Looks like oil pressure is lost somewhere and it's not reaching vvti phaser resulting in p0012
Yesterday I have changed timing chain set. Phaser is also changed but just found that phaser of 1nzfe is diff from prius cam phaser But still same engine shifting to battery and back is very rough. Lack of engine power Fuel average is bad, Only part left to change is oil pump. I m not sure will it make any difference. Why it's so tough to clear this code Any Prius expert please come forward
I’d like to post a solution to this! Or at least a possible one. Same scenario. P0012 after head gasket change. No response from VTC solenoid active test. Not a circuit or solenoid issue. Suspect oil flow issue to VTC after circuit diag showed no faults. Disassembled to inspect and found intake cam gear bearing to be spun under the #1 cam cap, thus blocking the flow of oil to VTC solenoid. We send heads out to be machined/rebuilt. Only thing I could think of is too much thick assembly lube on initial start up rotated the bearing. Inspected bearing and found it within spec. Set bearing to proper orientation. Fixed! I run an auto shop and I have personally done over 30 Prius head gaskets. I’ve never had this happen. BUT it did. To OP: if you did a chain to attempt remedy, and didn’t take off bearing caps (which no need to) you would have missed this. BTW a stretched chain on a Toyota always throws a correlation code, not solely P0012. I hope this helps someone out!
PismoJoe I am battling this same issue and have done pretty much everything the OP has done and have all but given up. Not sure if he mentioned it about his but mine runs like a top but only gets 33-35 MPG and I know the hybrid battery/system is in good shape. I am a little confused when you say instake cam gear bearing so could you elaborate a little please? Are you reffereing to the little shim looking pieces like this but have the little slots in them? 11821-37010 Genuine Toyota Bearing, CAMSHAFT
Yes, that is the one. So if that bearing rotates, it does not allow oil flow to the VTC gear or solenoid. There were no symptoms in my case, except for the sole P0012. No running issues at all. I will say this issue could cause a lower than normal oil flow to camshafts, so get it fixed! Here is a better picture; components 11811 & 11821 are the 2 pieces of the intake cam bearing. The top has 2 oil holes and the bottom is solid. There is an identical bearing for the exhaust cam as well, so check that when you get the #1 cam cap removed. I did not have to remove the timing chain for this fix, only the #1 cam cap and the timing chain tensioner with all cam caps loosened. Then I was able to rotate the bearing back into place and made sure it was coated with engine oil only. Have an extra timing chain tensioner gasket handy for this fix. I hope this helps you!
