Alright I got a 1999 4.2 V6 F150. I went to go smog it today and it failed due to the check engine light. The codes it came up with are:

PO141 - 02 sensor heater fault (bank 1 sensor 2)
PO161 - 02 sensor heater fault (bank 2 sensor 2)
PO171 - System too lean (bank 1)

I dont know what to do. Does anybody know how I can fix this and how much its probably gonna cost me???

 

Here's what I'd do, BEFORE throwing money out the door...

1. Check all the wiring for the o2 sensors and make sure the obvious is done. Like look at the wires, make sure there are no kinks, frays, missing wires, missing pins etc. Try to follow them back as far as you can.

2. Remove and inspect the o2 sensors. From the info you gave me, you have a 4 sensor, California emissions system, built for the 1999 emissions control year. So remove all 4 sensors, and look at them carefully. Even get a rag and some compressed air and clean them off. You can also use some QD (or equiv) electrical cleaner on them as well.

3. Generally a heater fault is only 1 of 2 things. Either a broken wire, bad connector, or the heating element has just flat out died.

4. That System too lean on bank #1 is merely the system telling you that because of the malfunction with the o2 sensor, it is making the engine run in a lean state. Which should clear up as soon as you figure out what is going on with those two o2 sensors.

5. o2 sensors do NOT last forever... in fact, I recommend just replacing them at 60k to 100k miles, or some place in between. They are relatively easy to replace, but on the flip-side, since you've got a California emissions system, you've got 4 sensors, which can be a $200 job, IF you do it your self.

Hope this helps.

 

the easiest thing to do is just go ahead and replace the front sensors. move your old front sensors to the rear.

get the codes cleared after you do this and things should be back to normal.

the reason i say go ahead and replace is because if you do all the tracing and find something wrong you will be replacing anyway. the front sensors usually last longer than the rears.

 

well it looks like it was probably a fuse. somebody recommended to me, check the fuses. I looked in the manual and didnt see any O2 fuses, so I started checking them all with a little tester. in the fuse box under the hood i found a fuse that was blown and the manual says its for "CMD, powertrain "... something like that... I replaced the fuse and disconnected the battery to reset the computer for codes then reconnected it. when I started it, the check engine light wasnt on and I let it run and drove it for about 30 minutes and its still off so Idunno, Im hoping thats what it was. Ill find out when I get another smog test

 

It will take a couple of drive cycles for it to throw a code again, if it is gonna.

Also you can't go back for another test right away b/c you will have a P1000, which means that the codes were recently erased. That is how they keep you from doing the battery disconnect down the street from the smog shop. I dont think the Auto Zone readers will pick up the P1000 either.

I see you're in Riverside, where did you find an Auto Zone that will still read codes?

 

you cant move your front ones to the rear thats probly the dumbest thing i have heard but whatever and you cant really remove them to inspect them the threads usualy strip right off of them if your o2 sensors are ready system too lean then yours systems lean and they are doing there good if the say o2 sensor malfuntion then there are messed up if you have a good read you can watch them and see if they are lazy aswell and dont replaxce them every 60 to 100k either and dont buy aftermarket they last 200 at least exspecailly in a highway driven truck

 

You most certainly can, as long as the pigtails are long enough to plug into the harness. We recommend that here all the time.

Not necessarily. If they do, then you do have to replace them. If not, you are golden.

Good advice - use only Motorcraft or Bosch sensors.

Note that the faults are in the rear sensors - their only function in life is to report on catalyst efficiency. They do not affect the way it runs at all.

 

I should have wrote that theres only 2 O2 sesors, my bad.. But I got the codes from the smog place, the papers they gave me had the codes on it. I took it down back to the smog place after replacing that fuse and driving it about 30 miles and it passed so it looks like I got lucky with just replacing that fuse.... As far as getting it scanned for the check engine light, if you can get a riverside penny saver, theres a coupon on the front page for a place called "meineke car care center" at 5500 vanburen. theres a coupon that says "check engine light free scan".

 

I was just wondering b/c I thought you said you got it done at Auto Zone-my bad.

My kid works at an oil change place at Pierce and Magnolia and I get it done there too.