P1035 code help

Hey guys

I need some help with a code. I got the oxygen sensor code for bank 1 sensor 1. And heater circuit code. So we put in a new 02 sensor. Reset the memory. Drive the truck for a while. Code comes back. We hook up the diagnostic computer. We can turn the heater circuit on and off with the snap on tool. The trucks fuel tables and fuel consumption stays the same. We checked for a damaged wire. The voltage is all good. Is there anything else that can be causing this?

Thanks!

I've never heard of a code reader turning rear O2s on and off, that would be against the law.

Also O2 sensor 1 is the front O2 and the rear O2 is also called heater O2.
Your truck measure how long it takes for the rear O2 to get to the proper temperature in the correct amount of time.
This is the way the government makes sure you are running cats.
If the PCM doesn't get this info correctly codes will pop up.
It could be that you have a bad Cat

I believe its common to turn off rear o2 sensors to avoid issues with no cats. Thats how my mustang is set up. Doesn’t throw a code then without the cats.


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It’s the sensor before the cat. There’s 2 before the cat that measure air/fuel and the two after the cat that make sure the cat is working fine. If it was the one after I would just disable it with my tuner.

Yes it's common to turn on and off the rear O2s but only with a Tuner device with non 50 state emission legal Tunes, not a "Code Scanner/Reader".
But you will never be able to pass an OBDII inspection, which by the way will be happening to all states eventually.



---------- Post added at 09:49 AM ---------- Previous post was at 09:39 AM ----------

Tomek6 said:

It’s the sensor before the cat. There’s 2 before the cat that measure air/fuel and the two after the cat that make sure the cat is working fine. If it was the one after I would just disable it with my tuner.

Click to expand...

Your just repeating what I stated.
I was giving you the benefit of doubt that you know what the O2s do, that's why I didn't go into to much detail.
Most people do not know the PCM by it's internal clock,
times the amount of time it takes for the rear O2s to come up to operating temperature with the correct values.
That all I was pointing out.

Lets start over, What mods are you running?

Are you sure the wire to the front is corrosion free and not damaged in any way?
I ask because quite a few owners have had trouble with the front O2s and wound up buying a new O2 wire harness.
Problem solved! Not saying that, that is what you need, just giving you information.

And are you sure you cleared the permanent code if there was one?

Doing the battery disconnect to reset the KAM, it does not clear all codes.
Most code readers will clear temp codes but not permanent ones, just double check.
Depending on the code scanner, you may have to run a full log, to see if any permanent exists.

Sorry I may have made that confusing. We didn’t turn off the sensors with the scanner. We merely tested weather the heater part of it turns on and off. Apparently you can do that with the snap on scanner. Only mods I have are 5 star tune and flowmaster super 40 muffler. Resonator delete. The exhaust has been like that since 2012. I’ve just recently got the 5 star tune but I’ve been having this o2 problem before the tune. I’m eventually going to get long tube headers so I’ll have to disable the rear sensors. It’s the front one that’s giving me trouble. We unplugged both sensors and checked the voltage going to the wiring harness. It’s the same on both sides. But only passenger side is throwing the code. Since the voltage is the same that leads me to believe there isn’t damage in the wiring harness.

Edit. We reset the permanent code.

It’s this sensor that’s the problem

I think your confused about the "Heated O2s".
It's merely a term, there isn't any voltage being sent to the rear O2s to heat them up.

Again it's just terminology!!!

The exhaust heats up the rear O2s and the PCM monitors how fast or slow it takes to heat up.
The PCM monitors millivolt change as the O2s heat up from the exhaust and the wire is so fragile it's is easy to miss if it's damaged.
I hope I made that clear.

Now for the front O2, it's most likely the wire is damaged and/or corroded or just a loose connection.
But other causes could be:
1) an exhaust gasket leak by the manifold to front cat pipe.
2) the replacement O2 is faulty
3) the cat has gone bad (it's happened a few times to members on this forum) even with low mileage.

Now most of us Raptor owners are running cats with headers It's just safer!!!
And it's easier to get your truck inspected.
There are threads about running High Flow Green Cats and using O2 spacers so you can leave the rear O2s "ON"

Do some more research before just jumping in.

I’m in Canada. They don’t do inspections here. As long as you don’t have a CEL you pass emissions. My other car had a big turbo and catless exhaust and I had the rear o2 sensors off with a tune so it wouldn’t get a code. Passed inspection many times. The rear sensors aren’t an issue on the Raptor. It’s the one between the manifold and cat.

I am seeing some water coming out of the Y pipe joint and the rest of the exhaust but that’s way further after the sensor.

If the wire is bad wouldn’t it read different voltage than the side that isn’t throwing a code? And if the cat was bad would it not be the rear sensor throwing a code?

---------- Post added at 04:05 PM ---------- Previous post was at 03:52 PM ----------

The front sensors are on a heater circuit.

This code refers to the front oxygen sensor on Bank 1. The heated circuit in the oxygen sensor decreases time needed to enter closed loop. As the O2 heater reaches operating temperature, the oxygen sensor responds by switching according to oxygen content of the exhaust surrounding it. The ECM tracks how long it takes for the oxygen sensor to begin switching. It the ECM determines (based on coolant temp) that too much time elapsed before the oxygen sensor began operating properly, it will set P0135.

Everything seems to be operating fine though so I don’t know what would be causing the sensor to not heat up fast enough. A leak before the sensor would make sense.

It still sounds like a lazy O2

I'd have to go back to Fordparts.com and pull up the OBDII Theory and Operation .pdf
I forget what the constant voltage is, is it 5 volts or 12 volts?

It's the resistance the O2 creates as they heat up from the exhaust that changes the values of both upstream and downstream millivolts signals