New to forum. Hope this is the right place to post. 2000 ranger Changed out my plugs with oem plugs. 5 week later i got the following codes. PP0172- P0175 And P0443.

Trouble Code:: P0172 (3.0L V6 VIN V Auto)
Fuel System Too Rich (Cylinder Bank 1)

Trouble Code: P0175 (3.0L V6 VIN V Auto)
Fuel System Too Rich (Cylinder Bank 2)

Trouble Code: P0443 (3.0L V6 VIN V Auto)
EVAP Canister Purge Solenoid Circuit Malfunction

Thought maybe a fluke, so cleared the codes.
Then two days later got 5 codes.
P0135
P0141
P0155
P1132
P1132

Trouble Code: P0135 (3.0L V6 VIN V Auto)
HO2S-11 (Bank 1 Sensor 1) Heater Circuit Malfunction

Trouble Code: P0141 (3.0L V6 VIN V Auto)
HO2S-12 (Bank 1 Sensor 2) Heater Circuit Malfunction

Trouble Code: P0155 (3.0L V6 VIN V Auto)
HO2S-21 (Bank 2 Sensor 1) Heater Circuit Malfunction

Trouble Code: P1131 (3.0L V6 VIN V Auto)
Lack of HO2S-11 Switching, HO2S Signal Low Input

Trouble Code: P1152 (3.0L V6 VIN V Auto)
Lack of HO2S-21 Switching, HO2S Signal High Input

Trouble Code: P0135 (3.0L V6 VIN V Auto)
HO2S-11 (Bank 1 Sensor 1) Heater Circuit Malfunction

Checked ohms on all heater circuit sensors. All were in spec. Sensors were old so replaced all 3 with bosch. Checked old sensors with a torch, one seemed slow to respond. All 3 new tested good for voltage switch with a propane torch test. So all 3 new sensors tested good for switch and ohms on the heater. This is a long post and I have tested a bunch of stuff. If anyone wants to help me, I will continue with this post. These codes are still present and it is definitely running rich.

 

All the O2s share one fuse in Engine Fuse box for their Heaters, fuse 13 in 2000 Ranger
Check that the fuse has 12volt with key on, and of course that fuse is not blown

P0443 EVAP Canister Purge Solenoid Circuit Malfunction<<<< also caused by no Power at fuse 13

Rich or Lean codes don't mean engine is actually running Rich or Lean, these codes are related to injector open times and computers calculations

Actual Rich running, i.e. smoke out the tail pipe, can be a fuel pressure issue or computer issue in 2000
1998-2000 Rangers used a true Returnless Fuel system, which didn't always work well, Ford changed it in 2001

Fuel pressure at the engine needs to be 55-65psi for computer to calculate correct fuel mix, there is no Fuel Pressure Sensor on any Ranger
In the gas tank is the fuel pump and the Fuel Pressure Regulator(FPR), these are both on the fuel pump assembly

The electric fuel pump is capable of 90+ psi pressure
The FPR has a spring valve set for 60psi pressure
when pump is on the FPR gets the fuel from the pump and sends any fuel over 60psi back into the bottom of the tank
If the FPR should fail to open you could have over 75psi at the engine/injectors
This would cause Rich running and rich codes

So I would get a fuel pressure tester, you can rent them or borrow them from some auto parts stores
There is a pressure test port on the engine
I would do this before anything else, just to take it off the table, or find out it is the issue

 

Thanks for the response. Fuel pressure is 60psi KOEO, and 62psi at idle. Fuel rail damper has no fuel in vacuum line. Did the injector leak test. Passed. No blown fuses. All 02 sensors have 12v. All heater elements ohm readings are near 7-8ohms. Read an article and made a test light with an incandescent bulb out of an old sensor harness. The bulb lights up, so the heaters are getting power. Air intake box is clear, filter clean, MAF reads in spec, intake air sensor (thermistor) is reading correct. No vacuum leaks but did a smoke test. Smoke came out of the IAC valve. Cleaned it and new gasket. Retest and smoke came out the breather under the round tab on the top of the valve. I don't know if that's right but if it's a breather makes sense to me. Tested the valve has 7-13 ohms which is in spec. Unplugged it while running and engine quit. That is what should happen from the info i have found. I have 18" of vacuum at 2200 ft above sea level. No exhaust restrictions. Alternator leaking diode test passed. TPS .8v closed 4.3 wot and voltage moves smoothly opening and closing. DPFE passed voltage and ohms testing. Took egr off cleaned it and check for blockages. applied vacuum and pintle moves up and down when vacuum is released. Took hose of egr applied vacuum ran rough. Took top off the evr solenoid put my finger of the hole and egr system is ok, and the solenoid has 12v. Coolant temp. sensor reads correctly to the pcm. It does blow black smoke and soot, and I am not driving it except to see if I have fixed anything.
So, I screwed up the codes in my fist post
P0135
P0141
P0155
P1132
P1152*
are still present.

 

Good to post your definition with the codes, these are from this page: https://www.therangerstation.com/tec...II_codes.shtml

P0135 02 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
P0141 02 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)
P0155 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

So all 3 O2 sensors report a Heater circuit fault
And its a pretty simple circuit

Fuse 13(12volt)-----------------------------O2 heater--------------------------------Ground(computer)

A heater is just a coil of wire, so with key ON fuse 13 sends 12volt to the O2 heater, that 12volts goes thru the heater's coil of wire and to the computer, if computer "sees" the 12volts it Grounds that wire and heater starts to heat up
If computer does NOT "see" the 12volts is sets the code for that one O2 sensor, so one of the above 3 codes

So there are 3 separate Ground connections at the computer, one for each O2 sensor
But only one 12volt source for all 3 heaters

For all 3 codes to be set I would, of course, suspect the one thing they have in common, the 12volts from fuse 13
(fuse 13 also powers EVAP solenoid, so P0443 fit no 12v at fuse 13 as well)

If you have 12volts at all 3 O2s with key on, then it can only be a computer issue, no other options that are reasonable, like 3 broken ground wires that only share the connector on computer
But the 3 wires on next to each other, pins 93, 94 and 95

One heads up, when testing voltage with a voltmeter you need to see FULL BATTERY VOLTAGE on the wire being tested
So with key on test battery voltage, if you see, say 12.5volts, then when you test the wire it should be EXACTLY 12.5volts, not 12.3volts
This is because a volt meter is a 0 amp load, if you see a voltage drop on a 0 amp load then there is a problem with the wiring, corrosion somewhere usually, so in this case when the "heater" is connected volts can drop to almost 0 volts
You can test with all heaters connected and see


Computer has 6 Ground wires, pins 24, 25, 51, 76, 77 and 103
Some are shared, some are not
So you could have a bad ground at the computer, and it only effects a few sub-systems, i.e. the heaters and causes Rich running
Pull off the connector and test each wire with OHM meter to ground
(you can also test for 12v, key on, on pins 93, 94 and 95)
If they all test as OK then computer is bad

 

Thanks Ron. So when you said One heads up, when testing voltage with a voltmeter you need to see FULL BATTERY VOLTAGE on the wire being tested
So with key on test battery voltage, if you see, say 12.5volts, then when you test the wire it should be EXACTLY 12.5volts, not 12.3volts
This is because a volt meter is a 0 amp load, if you see a voltage drop on a 0 amp load then there is a problem with the wiring, corrosion somewhere usually, so in this case when the "heater" is connected volts can drop to almost 0 volts
You can test with all heaters connected and see
"So can i back probe one o2 heater at the 02 side of the connector to check voltage and look for a discrepancy", or do i need to do all three sensors, on the sensor side of the connection at the o2 sensor.

 

All three O2s would need to be connected
Key on
Back probe for 12volts, this is a load test, should be a light blue/orange stripe wire on all 3 O2s, this wire is from fuse 13

Unfortunately, because of the codes, the computer is probably not grounding the heaters so not much of a load at all, lol

You can use a test light instead, that's a bit of a load, but hard to tell lower voltage by bulb brightness unless its really dim

 

Thanks Ron. Your help is appreciated. I got to some testing's today and here are my results.
Once I figured out the computer connection diagram, I have for pin out is upside down. Pin 93, 94, 95 have battery voltage. So, all good. Ground wires next.
24- ohms
25-NO OHMS
51-ohms
76-ohms
77-ohms
103-ohms
Well, there is a problem ground 25.
This is a solid black wire.
Million-dollar question is, where is the other end of this wire? The end on the computer looks good. I really do not want to unwrap that giant loom and follow this wire. Do you know where the other end is? If you do, I could just slice in at computer connection and run a wire to ground. Know what I mean? If I have to open that bundle of wires just afraid of doing damage to 22-year-old wires. If I have to, I have to. Thanks. Good news is I can't yet condemn the computer.

 

I am condemning the computer. The black wire was grounded out of the bundle to the firewall. I removed to gain access to the plug. All 6 grounds read about .5 ohms at 200 on the dmm. The heater circuits all read battery voltage at the computer plug in, and back probed at the oxygen sensors pigtail connections.

 

Yes, it does read like computer fault

 

So, should I start a new thread for info on replacing the computer or continue on here? There are used computers at a nearish u pull it yard.

 

Curt, Curious if the computer was the issue in the end? I am having the exact same issue.

 

Have not had time to look for one yet. Probably get to it in a couple weeks.

 

If I find a computer at the u pull it yard that is a 3.0 flex fuel auto transmission...And if it has the keys in it. Can I just take the ignition cylinder and put it, and the computer in mine? Then I wouldn't need to have my keys programmed to the junk yard computer? Right?

 

No,
You would need the ignition cylinder and key(s) and computer
But in a 2000 Ranger there is a separate PATS module, its above the Glove Box
But you can get that as well, just unplugs

The PATS module and computer are "married" at the factory, so one can't work without the other, a Ford Dealer can "re-marry" either if one needs to be replaced
1999/2000 had this setup(1998 had same but was a "pay extra" option, which wasn't that popular)
2001-2003 had PATS in computer
2004 to 2011 had PATS in instrument cluster, so also a separate module

 

pulled a junkyard computer, Ignition cylinder with a key, and the pats module. Put it in, and it started and idled perfect. It was too late to run it through a drive cycle. I will let all know if it cures the issues. THANKS RON D.

 

Good work

Thanks for the update, yes let us know if all is well after running it for a week or so

 

After testing of all the above items. The computer WAS BAD. Drove a few drive cycles, went for a New York State inspection and of course it passed. The new computer (pats and ing. cyl) Cured all the issues. So, 3 new O2 sensors and $40 for a computer, pats and cylinder back on the road. Thanks!

 

Good work

Thanks for the update