P0135 2002 F-150 4.6L

p0135 is B1S1 and that is passenger side. The sensor is original ford? confirm heater circuit resistance (2 and 1) between 3 and 30 ohms? All other pins resistance greater than 10,000 ohms? SWAG - an aftermarket part? Conform I am on correct diagram 12V is RD/YE wire control is RD/WH wire

Yes confirmation. That is the correct sensor and wiring diagram. Original sensor was FOMOCO but was replaced by bosch direct fit.

Update: I must have been tired last night. Retested ground side this afternoon. Voltage drop on ground side of circuit from o2 heater control harness side to the backside of C139(final connector before PCM connector) voltage drop was at 7 milliamps, good circuit. Second, when connecting DVOM to B+ and connecting the other lead to 02 sensor side heater control pin, I got B+ voltage, indicating that my driver is still grounding the circuit, however, I believe the driver may be cooked, as when hooking my scope back up I see the aforedescribed scenario. KOEO I have B+ voltage with the occasional PWM. When KOER, initial PWM for 2-4 pulses then stays at ground. I also went through the blah blah blah resistance checks provided by alldata to be safe and resistance checks for all associated tests passed as OL or within 3-30 when testing 02 itself. Based upon Voltage drop results on positive and ground side along with resistance testing I believe PCM is culprit. And other ideas or feedback is appreciated.

One last note. I scoped both 02 sensor heater control wires and the scope patterns are the same. Also both pins are side by side on the PCM. I assume both drivers are cooked since they are side by side in the PCM (pin 93 & 94, respectively). This was my original assessment and I have come back full circle to this estimation (PCM), but I'm definitely open to other ideas for additional testing ideas etc.

Quick info as I have a busy day -- BOSCH is not a recommended part - have you ohm' ed* the heater side - this is where Bosch's often fail, If you had to wire any part of this 'replacement' part that is also suspect. Later * heater circuit resistance (2 and 1) between 3 and 30 ohms?

I did. the heater circuit on the replacement resistance measured 11 ohms, so we are good on that.

A quick look gpt this - sure you did the list but not sure Trouble Code: P0135 (4.6L V8 VIN 6 Auto) HO2S-11 Heater Circuit (Bank 1, Sensor 1) Number of Trips to Set Code: 2 Trouble Code Conditions: During testing the heated oxygen sensor (HO2S) heaters are checked for open and short circuits and excessive current draw. The test fails when the current draw exceeds a calibrated limit or an open or short circuit is detected. Possible Causes: •* Vacuum hose disconnected on exhaust gas recirculation (EGR) system module (ESM) applications •* Short to VPWR in the harness or HO2S •* Water in the harness connector •* Open VPWR circuit •* Open GND circuit •* Low battery voltage •* Corrosion or incorrect harness connections •* Damaged HO2S heater

Update: Just for clarity's sake, I dug the original o2 out of the dumpster, Ohmed the heater circuit, and to my satisfaction, there was infinite resistance. Burned up heater element in original 02. As mentioned in previous post, new 02 has adequate resistance (9-11 ohms after multiple readings). So I definitely needed an o2, but, and correct me if I'm wrong. The literature says the the circuit should be PWM .1/100 KOEO .1/100 KOER. I only briefly see PWM in both scenario's prior to the PWM either staying at B+ KOEO and 0 volts KOER. Will the PCM on these begin PWM then notice a fault and immediately shut down PWM or does it wait for the two drive cycles, log the code after running the test, then shut down PWM? One other note is that it appears all four sensor heater circuits are not working. I could see the front two not working in the event of a short as they run through the same connector (C139) to the PCM, however 2,1 & 2,2 run through a different connector entirely (C101). The only place these four meet is at the PCM pins 93, 94, 95, & 96. Is there a way I can test these pins on the PCM for an internal short? My thoughts would be disconnect PCM and resistance check between 93 & 94, and a resistance measurement other than infinite should indicate a short in the board right? Thanks for all your help so far. This sucker has been a challenge.

Correction: These four are also fed power via the same fuse/relay, however, they all have proper voltage coming from B+ side of the heater circuit.

thinking out loud as they say- testing 93 to 94 IDK what you SHOULD see - should be open EXCEPT for the voltage sense ability?.. I am always see the issue before PCM (93, 94) the wiring to get the voltage to thise pins and the PCM not happy with it senses.... My trouble tree has us at current place with a replace PCM as next step I do not like to condemn PCM's I need time to reevaluate. There are NO other codes? Original issue P0135 (open Htr) and replacing sensor did not clear the issue? A thought - Could the pin (93) - internal PCM be permanently grounded ? A challenge - Anal question - above you posted "2,1 & 2,2 run through a different connector entirely (C101)." typo? C110on my dia? LATER

How much trouble to swap B1S1 and B2S1? I am back to the 'bosch' concerns.

I could swap them easily. I was planning to ohm the B2,1 sensor next to see if perhaps that heater was also burned up. Both appear to be factory original at 223k. I'll swap, check, then update.

You are correct. C110, that was a typo. I also do not want to unnecessarily condemn PCM. Other codes are P1131, not switching correctly, stuck lean. It wasn't switching well at all on live data (.2-.5). This data is what led me to condemn the 02 originally. After replacement new 02 signal follow B2,1 perfectly. I also have these other codes. PO231, PO460, PO740, PO758, P1460, P1760. I have output tested all codes relating to transmission shift solenoid, TCC, etc. according to spec and all operate when commanded to do so. Next step is dropping pan and checking internal harness along with connection points as per pinpoint test A. I originally thought perhaps the power feed through power relay (which runs through 02 sensors on back to transmission) might been the connection between all these codes, however, after testing 02 heater circuit I'm fairly confident the trans and 02 codes are unrelated. Furthermore, customer complained of rough shifting months ago, when brining it in for CEL this week, he mentioned the shifting has been fine ever since but that the CEL illuminating was why he brought it in. Another concern is communication with my scan tool. I am running an autel MS906BT. Normally the tool, once linked, will save the vehicle information along with current DTC's in the scan tool vehicle history. This one, however, will not save the DTC data in the vehicle history (curious, I just replaced an engine on a 2000 excursion and saving DTC data to scantool was not a problem). This also makes me suspect PCM. Anyway, this is everything I know up to this point about all related systems if you can make heads or tails out of that I'm appreciative.

Interesting your scanner will not save data - is there anything in vehicle "freeze frame" ? or is it also clean?

That's what I thought. I've had the scantool about 3 months now but for every other car except this one I've had no problem saving the history. I had to take screenshots of the DTC's on this guy's truck! PO 135 Freeze Frame: closed loop LOAD: 53.73% ECT: 174.2 F SFT1 5.47% LFT1 5.47%

well that freeze frame is no help, was hoping to see something related ie a voltage issue, open loop, lost info . I feel we are down near the end of hope for PCM. The monitors are setting I guess ? Charging is good - Have you swapped o2 sensor? When your scanner command s Htr can you see circuit activity?

I haven't swapped O2's or commanded on the heater circuit. I was using my scantool as a scope so I couldn't do both at the same time (scope/command on) and needed my wife to bring back the laptop. Will check later and update.

I'm new to using this scan tool and when I enter output test mode I've got like 30 options for HO2S. I included all the ones for HO2S 1,1 then commanded on while I back probed the Heater circuit with my scope. When commanded on, heater circuit PID still says off and voltage on scope shows 12 volts with a 250 millivolt oscillation above and below B+. I am assuming that when I command on in output test mode that the entire sensor (heater circuits and 02 signal circuit) should come on if working properly; is that correct?

Update: Thanks for the tip on checking the 02 sensor!!! Remember in my initial post, I thought I had a short to Power on the control side of the heater circuit? Well I did. It was intermittent, however, and the one time I saw it, it went away and I never saw it again, which made me think I was just tired and had my meter in the wrong pin, until I unplugged the 02 2,1 sensor. The resistance was fine on the sensor but the process of wiggling the sensor harness to remove the sensor reactivated the short on the control side. So since then I've begun pulling off the intake as therr is really no other way to get at the harness back there. I'll repair and hopefully the computer is still intact afterwards. I'll keep you posted.