Car suddenly had a CEL appear, but seemed to be running fine. Pulled the codes and found: 4112 Cam Phase Sensor 1212 Some MAF / O2 voodoo Could a bad phase sensor actually induce the 1212 code, seeing as it seems to relay information about cam rotation that may be used in equations calculating mixture? I've read the fixes for both of these issues, but I'm trying to decide which one to tackle first, or if they are both related. Since this is the first CEL I've had since the major, I'm leaning toward sudden failure of the phase sensor that (hopefully) is causing inaccurate MAF errors. Thanks guys!
The cam phase sensor is located on the back of the 1/4 intake cam (looking in from the back it's on the right hand side). Have a look and make sure you don't see any signs of oil leaking from there. If you do it could be the rear cam seal has let some oil get inside the sensors housing and messed up the electronics. If you need to change the seal, or sensor/both for that matter, it can be done with out much trouble. You will need to remove the air box for better access. For the MAFs code you should remove the air box and have a look inside the MAFS to make sure it isn't all oily. Be sure it is clean and that the connectors are clean and connected properly. You haven't washed it recently have you?
Hasn't been washed too recently. Drove it plenty of times since the last washing without issue. Both issues seem like pretty easy fixes, but it struck me as odd that they both seemed to occur all of a sudden in two somewhat separated systems. Suppose one of the codes could have been old, but I've never seen my CEL 1/4 come on. The 5/8 has flashed occasionally if I accelerate too hard before the car is warm, but this was the first 1/4. I will pull the cover and take a look at the MAF later this week.
http://www.the348.com/technical/Tech/348.html#Phasesensor A bad phase sensor could contribute to an O2/MAF "mixture out of range" error.
Cool. That's what I was hoping. Thanks you two. Will go do my wrenching and let you know how it turns out.
Just wanted to follow-up for the good of the fellow wrench turners. Got my phase sensor in today (thanks Daniel!) and went to remove the old one. Lo and behold, the connector had disintegrated. Looks like the old plastic just fell apart due to heat stress or simple aging. Anyhow, using the procedure on the348.com I easily pulled the cover, replaced the sensor, and then remounted the cover. For future reference, the cover will go on multiple ways so make a note of where the phase sensor is positioned when you take it off. I believe mine as around 1:00 or so, with the sensor cable exiting the housing around 7:00. Hopped in and started her up. She ran a bit rough, which is likely due to me not pulling the battery cables off (I didn't pull the air box off either.. I know, shame on me), so I cleared the codes and restarted the car. Idle settled in and she's running great once more. So ND you were 100% right. The phase sensor will toss an O2/MAF CEL as well. Thanks you two.
Good post! Very nice follow-up (especially your tip to mark the housing so that other 348 Brothers have an easier go of it in the future). Nice to learn that you got it sorted out. DRIVE ON! Oh, by the way, like yours, my phase sensor's black plastic electronic connector housing had disintegrated. Easy replacement, though.
There's something about the phase sensor these days!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Anyway, when washing the car, I am now assuming that any amount of water getting into the engine compartment may ruin electrical connections ie. phase sensor connections or O2 sensor connections etc... Right?? Thinking back, I think the problems started with the messed up crazy codes with my 1/4 check engine light that turned out to be the phase sensor connection right after I washed the car a couple of weekends in a row!!!
I first cover my engine with towels, then plastic trash bags, followed by a big plastic table cloth, then I wash it. I'm not taking any chances of getting something wet.
Sounds good. I bought a $4 clear plastic shower curtain at my nearby grocery store. I cover the entire engine compartment (motor off and cold)with it and it keeps the whole engine compartment dry during power washing. But I drive in the rain (obviously without the shower curtain!) and don't experience problems. Who knows...
The sensor itself is sealed, but the external connector is not very tight. Might not hurt to put a small bead of silicone sealer or non-conducting grease around the connector prior to snapping it in. Based on the state of my old plastic, these connectors probably crack and let water in after a certain amount of time. Just a guess though.
Put about 25 miles on her this morning and the 1212 resurfaced the first time I accelerated hard. Think I'll reset the ECUs and see if that clears it up. If not, I'll replace both O2 sensors and pull the MAF to clean it. Hoping it is just some leftover bits in the ECU that need some reshuffling. 8)
Now I'm curious... Perhaps you were going to tell me "that's why you should disconnect the battery?" lol Anyhow, I went out on lunch and reset the ECU. Drove four about 45 minutes afterward without an issue. May not be problem solved, but seems ok for now.
