P1151 code has come up. I replaced the sensor as it was never done, cleared the code and it came back. So I’m asking for so help and ideas as to what to do next or what people have found to be the most likely cause.

 

Which specific sensor did you replace?

 

That's neat. So Fuel Sys1 CL-Fault and Fuel Sys2 N/A means that the PCM has decided that there is a DTC specific fault and it is now operating under Failure Mode Effect Management - FMEM. FMEM in this case means that the PCM has decided that the Bank2 O2 isn't working right so it's going to use just the B1 sensor for closed loop on both banks. Notice that fuel trims for both banks are identical. That's because it's applying fuel trims from B1 to B2 as well.

When the PCM tells me something is wrong with the B2 O2, I believe it *but* it's helpful to see what it's seeing so that I can more quickly determine if I've fixed it than just waiting for a code to come back. For that you need to log B2 O2 (O2 sensor 21) voltage, first at idle. If there's something wrong with it at idle, that's easiest. If it only does it at 80mph at WOT, not so easy. So log both *FRONT* O2 sensors and compare their waveforms. You'll need to clear the DTC first to get it out of FMEM so the PCM can jack around with B2 fuel trims in an attempt to make the sensor start working. Report back.

 

driver side O2 sensor upstream

 

At the time you took your readings shown, the motor was not up to temperature.
195 to 200 is the normal range, otherwise fuel can be a bit rich and add some confusion. The cylinder head temp sensor detects this and treats the fuel as needing to be a bit Rich as in cold starts.
Test only under full operating temp.

 

Unfortunately I understand about 1/3 of all of this.

 

Challenge accepted.

O2 sensors make their own voltage when the right conditions are met. No voltage means lean (if you don't know rich/lean, google is what you need here) more voltage means rich. They can only make like .9 volts, tops. No voltage can also mean a dead o2 sensor or an open in the wire between the PCM (powertrain control module) and the o2 sensor. P1151/1131 are set when there is no voltage or voltage won't go beyond a threshold like .1 volts (IDK what the actual threshold is). Sometimes these DTC's are set because the motor is actually running that lean so even a healthy O2 can't make enough voltage.

The first thing I do when I'm diagnosing 1151/1131 is try to determine with a datalogger which of the 2 scenarios above that I'm dealing with. Is it a dead sensor/open circuit where voltage stays at 0, or is it just a lean motor that can't make the sensor go rich? The way I do that is to try to force the sensor to make voltage by making the engine run rich. The PCM also tries to do this. What I was talking about in my above post is that your PCM has given up on trying to make the sensor go rich and has indicated that by going into "closed loop, fault". Closed loop is normal, but in 'closed loop, fault' something is broke. Closed loop means that the PCM is reacting to O2 sensor data about how rich or lean it is and responding in a 'closed loop' of information. Your motor is still doing this, but it's only using the other o2 sensor, having decided that the driver's side sensor is unreliable. That's the fault part- ignoring one sensor and using the other in its place. (Open loop means o2 sensors are ignored and the fuel added to the motor is based solely on MAF sensor voltage)

So how do you force an O2 sensor rich? Clearing the DTC will make the PCM forget about the fault and try to force the sensor to go rich. You can observe this process with your datalogger and observing fuel trims for bank 2. It will look like this: once memory is cleared and the engine is started, o2 voltages will be low. The PCM will add additional fuel until they go rich. For the driver's side it will end up adding a lot of extra fuel because we know there's a problem going rich. Observe the voltage when the short term fuel trim for the driver's side goes crazy high. If it never budges from zero, suspect a bad sensor or a wiring problem. If it makes some voltage but not as much as the other sensor, the sensor might not be malfunctioning and messing with it might just be a waste of time. The cave man method of forcing o2's to go rich is by just squirting carb cleaner or propane into the intake tract. If you squirt enough in there to make the engine stumble and the sensor is still on 0, suspect a sensor or wiring problem. If it goes rich, the problem is elsewhere.