Daily Driver: O2 Code after hot soak?

[Arnold]

My 01 Focus 2.0 sohc set a P0135 code a year or so ago haha.
 I checked it and got that code. Erased it. Did not come back. Good.
Then after a while it did. Ditto. Finally it would not stop coming back.
Car still ran fine. Finally I figured out that it ONLY came back after a re-start hot soak. Erase the code and drive it and it NEVER came back. Shut it off and hot soak..it came back EVERYTIME. Needs to be a hot soak not just a re-start.
  Gas mileage dropped about 40% pretty much instantly one day and raw unburned fuel smell made the car next to impossible to drive. Time to fix it.
 SOoo I ordered an oe sensor and figured I would at least get started by getting the old one out.That was next to impossible. I got it out and it was pretty carboned up..I could see through the holes in it. Nothing to lose so I soaked it in a container with Seafoam in it for a few days.
 Stuck it back in and the car NEVER! had this much pep. Wow! I never would have thought that cleaning an 02 sensor could do that.Fumes gone.
lol..P0135 again after hot soak.
 I read that on these cars the fuse and the wiring can set this code too.
I could not find any info whether this can happen intermittently?
  The new sensor will go in when I get it just to see if it is the sensor.

   Now I feel like taking the sensors out of my other 2 vehicles and cleaning them too. One has 4 sensors. GRRR. The other I think only 1.

[papastoyss]

Would it be possible to pull the fuel rail & hotwire the fuel pump to see if the injectors are dripping fuel while the engine is off & fully warmed up?

[rooster]

po135 is the heater circut malfunction in a o2 sensor! Look for a bad ground!
My 2 cents!!!!!

[Arnold]

Thank you very much guys! I really appreciate your help!

 Papastoyss..Hmmm...I never thought of that. Thanks! Makes sense. Dripping injector loading it up with excess fuel after hot..then a soak..then firing it up super rich. I am not going to bother pulling the fuel rail just yet to see. This all started a year ago..and it was just the other day that the fuel mileage plummeted..THEN the fumes and I could not really drive it.
Cleaning the O2 sensor..ended the fumes and gave it way more pep. SOoo there was clearly a problem there that just develpped.So I am going to drive it this way until the new sensor(0rdered) gets here. Then I will stick it in and see what that does. Thanks!

  Rooster..I know that that code is the "heater circuit malfunction" and I did read that it could be a wiring problem. I did not know that it could be a bad ground? Thanks for that! I did not go any further with it because it
ONLY does it AFTER a hot soak. I did not think it could be an intermittent wiring problem. Putting a new 02 front sensor is a 2 second job..lol..after you get the old one out haha. Just lift the hood..(RUSTED exhaust manifold heat shield has already been cut back LOL for access)(( the nuts and studs are pretty much rusted away..may as well wait a bit longer and it will come off by itself haha.)) I am going to put the new sensor in first and then go from there.

  Thanks guys!

[wayne petty]

one might want to read this... from ford.. on how the 2001 OBD2 system thinks...


http://www.motorcraftservice.com/vdirs/diagnostics/pdf/obdsm109.pdf

page 27 of 65 is the proper page..

but read more than just that one page.. its an AH HAA moment..


here are links to the wiring diagram for the engine control system

http://www.autozone.com:80/autozone/repairinfo/repairguide/repairGuideContent.jsp?pageId=0996b43f802e80b0

so you can see how its wired...

[wayne petty]

well.. that was not hard to find the oxygen sensor wiring diagram.. its the first page of the az link..

or here...
http://repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0996b43f/80/24/02/14/large/0996b43f80240214.gif

seems the power hold relay at the top of the diagram in socket K13 supplies power to both oxygen sensors and the Maf sensor.  i might want to either inspect or replace that relay.. cheep insurance.. probably not a lot of money.. could have dirty /burned contacts..

the oxygen sensors heaters have a fuse at location  #F18  
one might also want to check the grip the fuse socket terminals have on the blades of the fuse.. ford actually has a small spring scale to test extraction resistance on fuses and relay terminals..  i take my carbide probes and work the tongue of the terminal to increase the grip.


so if you have one of the harbor freight plug in amp meters you could check the current draw... see if its drawing what the scan tool actually displays...

the oxygen sensor heaters seem to be grounded through  the computer via PCM pins 100 and 93...



does your scan tool graph the data stream .. some do...

i have seen on some scan tools.. the amp draw display of the oxygen sensor heaters... probably why they ground them through the computer.. it allows the PCM to monitor the health of the oxygen sensor heater elements and connections by monitoring the amp draw..  open heater elements.. dirty connections.. easily picked up..

[Arnold]

well.. that was not hard to find the oxygen sensor wiring diagram.. its the first page of the az link..

or here...
http://repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0996b43f/80/24/02/14/large/0996b43f80240214.gif

seems the power hold relay at the top of the diagram in socket K13 supplies power to both oxygen sensors and the Maf sensor.  i might want to either inspect or replace that relay.. cheep insurance.. probably not a lot of money.. could have dirty /burned contacts..

the oxygen sensors heaters have a fuse at location  #F18  
one might also want to check the grip the fuse socket terminals have on the blades of the fuse.. ford actually has a small spring scale to test extraction resistance on fuses and relay terminals..  i take my carbide probes and work the tongue of the terminal to increase the grip.


so if you have one of the harbor freight plug in amp meters you could check the current draw... see if its drawing what the scan tool actually displays...

the oxygen sensor heaters seem to be grounded through  the computer via PCM pins 100 and 93...



does your scan tool graph the data stream .. some do...

i have seen on some scan tools.. the amp draw display of the oxygen sensor heaters... probably why they ground them through the computer.. it allows the PCM to monitor the health of the oxygen sensor heater elements and connections by monitoring the amp draw..  open heater elements.. dirty connections.. easily picked up..

  Thanks very much Wayne! Cheap insurance..yes I do llke that .I am going to find that relay and the cost of it. Yes,my scan tool does data stream,live,freeze frame. To be honest..I never really looked that close. I just saw the P0135 code. The car ran fine and this only happened during hot soak so I just left it. Gas mileage :cry: and fumes :roll:came instantly a year later= gotta fix that now.I figured I would do quick first. Quick was NOT getting the O2 sensor out. Cheap was NOT the cost of the oe sensor. Cheap was ordered online.Should be here soon.Thanks again!

[wayne petty]

once you eventually get the oxygen sensor out..

while you are looking in your tool box for the BFH oxygen sensor removal tool....

look in the drawer for the dual ended spark plug hole thread chaser.. the one with the 14mm threads on one and and 18 mm threads on the other.. the 18 mm end is the proper thread to clean the threads...

many parts stores have oxygen sensor loan a tool sets with various shapes of tools..

this is a tool that might help get the sensor out.. you might want to disable the air bags by unhooking the battery for at least 10 minutes first...

http://www.tooldesk.com/automotive/LIS43900-Oxygen-Sensor-Remover-Lisle-43900.aspx

Oxygen Sensor Remover Lisle 43900



Part Number: LIS-43900
Pneumatic Action Removes Oxygen Sensors.
Use this set with an air hammer to remove stubborn, baked-on oxygen sensors. The pneumatic action works where conventional sockets won't. The compact design allows easy access under the hood. To install sensors, use the socket only with a 3/8" drive ratchet.


should be available easily with the part number above.

[Arnold]

once you eventually get the oxygen sensor out..

while you are looking in your tool box for the BFH oxygen sensor removal tool....

look in the drawer for the dual ended spark plug hole thread chaser.. the one with the 14mm threads on one and and 18 mm threads on the other.. the 18 mm end is the proper thread to clean the threads...

many parts stores have oxygen sensor loan a tool sets with various shapes of tools..

this is a tool that might help get the sensor out.. you might want to disable the air bags by unhooking the battery for at least 10 minutes first...

http://www.tooldesk.com/automotive/LIS43900-Oxygen-Sensor-Remover-Lisle-43900.aspx

Oxygen Sensor Remover Lisle 43900



Part Number: LIS-43900
Pneumatic Action Removes Oxygen Sensors.
Use this set with an air hammer to remove stubborn, baked-on oxygen sensors. The pneumatic action works where conventional sockets won't. The compact design allows easy access under the hood. To install sensors, use the socket only with a 3/8" drive ratchet.


should be available easily with the part number above.

  WOW!   What a GREAT TOOL! Never heard of one of those! Wayne you are a great source of information! Someone sure had their thinking cap on in the design of that. Think of the applications with a few modifications where that could be used!

   I gave mine the Seafoam penetrating oil for a day..then the PB blaster for a day. Then the torch. Nope. Then I sprayed it with the above. Nope.Then I used parraffin wax. Nope. Then I drove it and got it hot and did the above again. Nope.My O2 sensor socket started to chew up the O2 sensor and I was just about to break it off to use a conventional 6 point.
Really made me WANT an impact ratchet(there was no room for my gun or extension)I decided to give my old 12 point Gray 7/8 combination wrench a LITTLE try before chewing it up. Out it came. I am sure all of the above had an effect. Once loosened it came out with my fingers really nice.I did not even see a need to chase the threads. The sensor threads were real nice too. Left it in a container of Seafoam for a day and then stuck it back in. WAAAY better. As in driveable. Still the cel after hot soak.