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Check engine light, on symptoms?

Tiny
PAINT 4440
  • MEMBER
  • 2008 FORD EXPLORER SPORT TRAC
  • 4.0L
  • V6
  • 4WD
  • AUTOMATIC
  • 186,000 MILES
We got a check engine light about 2 months ago and after reading codes and some research determined it was most likely the O2 sensors. I do most of the mechanical work but due to access of these sensors I took this vehicle to a shop. They did a diagnosis and said all 4 sensors should be replaced. That did not clear the check engine light so they did a lot more diagnosis and still could not find the problem. They wanted to replace the ECM, but we declined because you can get into a replace this, replace that and it gets very expensive. The current codes as of today are following:

All preceded by P O 135, 141, 155, 161, 403, and 443.

Also, during this time, there was a short time where the battery would be drawn down and to start it, I would have to jump start. This was only an initial startup in the morning. I have checked all the fuses and found none blown. I am not sure if any of the relays are bad.

Anything you can suggest would be greatly appreciated.

Thank you in advance for your help.
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Monday, January 2nd, 2023 AT 10:12 AM

23 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,173 POSTS
Hi,

I went through the codes you have. Interestingly, the first 4 codes are all 4 oxygen sensors, and the diagnostics for 141, 155, and 161, all say to refer to P0131.

I made a list below of what I found. I like doing this for my own reasoning. LOL It helps me think things through.

P0131 - heated o2 sensor bank 1 sen 1

PO141, 155, 161, - likely caused by P0131 (banks 1 and 2)

P0403 - EGR

P0443 - EVAP/Purge control valve.

The idea that there could be a stuck EGR, or Purge control valve could be leading to a very lean fuel mixture. By chance, do you have a live data scan tool?

If you do, could you check the short-term fuel trims when the vehicle is at operating temperature? Also, monitor each of the 4 oxygen sensors and let me know the voltages you are seeing. Note that the voltages should move around, so if any are stagnant, let me know.

One last thought. Has anyone checked the EGR or purge solenoid? It seems to me that either we are getting an extremely lean fuel mixture, or we have a wiring problem. The sensors are not my first suspects.

Let me know.

Joe
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Monday, January 2nd, 2023 AT 7:15 PM
Tiny
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Good morning, Joe,

Thank you for your reply. I took those codes from a real basic reader. I will use a more detailed reader and see if I can get the voltage changes that you suggested. Not sure where the EGR solenoid is or what it looks like? Could you help me out with that one? Thanks

Greg
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Wednesday, January 4th, 2023 AT 7:23 AM
Tiny
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  • MECHANIC
  • 108,173 POSTS
Hi Greg, I attached a pic below showing the EGR and components. Take a look at them and let me know if that helps.

Take care,

Joe

See pic below.
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Wednesday, January 4th, 2023 AT 7:40 PM
Tiny
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  • 14 POSTS
Hello Joe,

Not sure if this GIF will go through or not. Let me know. My reader does not do fuel trims.
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Saturday, January 7th, 2023 AT 1:30 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

Yes, the pic did attach. It shows oxygen sensors. Are you able to check the voltage for each sensor?

Let me know.

Joe
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Saturday, January 7th, 2023 AT 8:02 PM
Tiny
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Hi Joe, I was having difficulty downloading that info. Will try again tomorrow.
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Saturday, January 7th, 2023 AT 8:42 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

No problem whatsoever. I will watch for your update.

Take care,

Joe
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Sunday, January 8th, 2023 AT 8:58 PM
Tiny
PAINT 4440
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  • 14 POSTS
Hello Joe, I am attempting to send Bank 1 Sensor 1 reading. Let me know if you receive it and I will forward the other readings. Thank you.
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Thursday, January 12th, 2023 AT 11:12 AM
Tiny
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Joe, Bank1, Sensor 2.
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Thursday, January 12th, 2023 AT 11:19 AM
Tiny
PAINT 4440
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Joe, Bank 2, Sensor 1.
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Thursday, January 12th, 2023 AT 11:25 AM
Tiny
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Joe, Bank 2, Sensor 2.
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Thursday, January 12th, 2023 AT 11:28 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,173 POSTS
Hi,

I got them. I'm not familiar with your scanner, but everything appears okay. While the engine is running, do the voltages change when you hit the throttle? Also, were you able to get the short-term fuel trims?

Let me know.

Joe
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Friday, January 13th, 2023 AT 8:05 PM
Tiny
PAINT 4440
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Hi Joe, I haven't checked the voltages for changes and I'm not sure that my tester checks fuel trims. At the moment the vehicle is in the shop for a totally unrelated situation. The right rear wheel nearly came off when the 5 studs sheared off.
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Tuesday, January 17th, 2023 AT 11:48 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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No problem whatsoever. When you get the vehicle back, check to see if the voltages vary. As far as the wheel, wow! What caused them all to break?

Joe
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Tuesday, January 17th, 2023 AT 6:07 PM
Tiny
PAINT 4440
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Hello Joe, we finally got the rig back. Not sure the 'why' for the studs snapping off but it was suggested that one was missing. Not sure that would cause all the others to come loose. Back to the check engine light. I will check for voltage variation, but my code reader does not check fuel trims. Any suggestions? Thanks.

Greg
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Thursday, February 2nd, 2023 AT 7:02 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

No problem, Greg. When you have a chance to check the sensor voltage, here is a link to help. The sensor voltage should be helpful.

https://www.2carpros.com/articles/how-to-test-an-oxygen-sensor-02-sensor

Let me know.

Take care,

joe
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Thursday, February 2nd, 2023 AT 6:51 PM
Tiny
PAINT 4440
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Hi Joe,

I have some readings for you. These are off a data stream that I froze

Short term fuel trim B1 0.0%
Long term fuel trim B1 5 5%

Short term fuel trim Bank 2 0.0%
Long term fuel trim Bank 2 7%

Oxygen sensor output voltage
(B1-S1) .925 V
(B1-S2) .090 V

Oxygen sensor output voltage

(B2-S1) .930 V
(B2-S2) .915 V
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Thursday, February 9th, 2023 AT 11:02 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

The short-term fuel trims are at 0. Was it checked when the engine was at operating temperature? In a perfect world, 0 is perfect. However, it is unlikely.

The O2 sensor voltages are within spec but to the high side. Let me know if you checked the trims when it was warm or if the saved data was when it was warm.

Let me know.

Joe
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Thursday, February 9th, 2023 AT 5:47 PM
Tiny
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Hello Joe,

I redid the fuel trims. Following are the readings and I am going to attempt sending a graph as well.

Short term fuel trim bank 1 varied between -.08% and 3 9%.

Long term fuel trim bank 1 stationary at 3 9%.

Short term fuel trim bank 2 varied between 08% and-1.6%.

Long term fuel trim bank 2 stationary at 5 5%.
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Sunday, February 19th, 2023 AT 8:31 AM
Tiny
PAINT 4440
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The video of the graph was way too big.
Hopefully the varied numbers I sent will help.
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Sunday, February 19th, 2023 AT 8:33 AM

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