Backfire and then all good

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Sam Odajima

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I cleared the codes last night and drove around and the only code that came back was the P2195. I looked at the live data and the freeze frame and it looks to be in a lean state. I've never tried to "Wake up" an O2 sensor. Can you tell me how to do this?
 

BRIANGEE

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Sure, first select your Bank 1 sensor 1 PID on your scan tool so you can monitor it's activity. Then remove something along the intake to be able to introduce some propane. I use propane since I have a blow torch w/ a small bottle hooked up and I just open the gas valve - propane is heavier than air so if it does go all fireball on me I will still have my eyebrows. If you use starter fluid or something else be careful because some of that stuff is pretty volatile and if it ignites you'll be smelling your crispy eyebrows for a while not to mention torching the truck. Last time I had to do this test I removed the plastic air funnel downstream of the air filter and introduced propane there. If you're using a spray be careful not to hit your MAF or Air temp sensor which are both right there. When you release the propane watch your O2 on your scan tool... what you're wanting is for it to react to the rich condition you've just created. It should go from lean to rich (probably from.1V or so to .8) and it should stay there for a while as long as you're pumping propane in.

On a good O2 sensor you would expect to see it switching very quickly back and forth between the upper and lower ranges. If it's sluggish, if it pegs lean (your issue) or rich there's an issue. A parts changer would be ready to throw in an 02 sensor but don't be tempted to do that just yet as you could be potentially shooting the messenger at that point. All we're doing is seeing if the messenger is credible or not - if not then we'll shoot him.
 
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BRIANGEE

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If it doesn't react to the propane at all then I would say you're safe to condemn the O2 sensor. Prior to that you can just watch the scan tool and snap the throttle and look for reactions - if not then I would break out the propane.
 
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Sam Odajima

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I hooked up my reader and its showing 0.0000V reading for my O2 sensor in both the freeze frame and the live data. Doesn't matter how I rev the engine, the O2 sensor still reads 0.0000V.
 

1955moose

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On top of what Brian described on propane enriching to find why it's lean on bank one sensor one, you might want to smoke the intake. 4.6/5.4s generate a lot of heat that breaks down vacuum hoses near the firewall. One leaking hose can create a lean condition, that can cause the computer to trip a lean code. You can do this old school, by spraying down all the hoses. But a smoke machine is quicker, and more thorough.

Sent from my N9131 using Tapatalk
 

BRIANGEE

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It's probably a bad sensor but if it were me I'd like to be 100%.

A few thoughts come to mind on what you could do:

1) If the heater circuit were bad it might take a while to heat up to the proper temperature and give readings. You might want to putt around the block and then check to see if the O2 is reacting.

2)Check for voltage on the heater circuit wires at the 02 - do wiring integrity checks.

3) Propane in the intake. Look for reaction on the scan tool.

4) Check your fuel trims to see if they corroborate w/ the 02 data.
 

BRIANGEE

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On top of what Brian described on propane enriching to find why it's lean on bank one sensor one, you might want to smoke the intake. 4.6/5.4s generate a lot of heat that breaks down vacuum hoses near the firewall....

Sent from my N9131 using Tapatalk

I would expect to see some sort of activity on the O2 though - especially during revving the engine.
 
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Sam Odajima

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Thanks for all the replies. I went to test the O2 sensor and found the wiring harness was cut and no O2 sensor. Fixed the harness and a new O2 sensor has been installed. No more codes. My main concern is that the O2 sensor is pressing against one of the ac lines going to the rear ac. Should I put some wrap around the account lines or O2 sensor?
 

BRIANGEE

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Probably wouldn't hurt but what the heck was the previous owner trying to do LOL? It reminds me of a guy I know who was failing emmisions testing and removed the cat converter, knocked the 'honeycomb' out of it and then reinstalled it. Of course he failed again and I was like... What the heck did you expect? lol
 
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