2003 Ford Escape Check Engine Code P0136

Hugh Streep · Posted at Wed Nov 04, 2009 7:06 am

Engine Performance problem
2003 Ford Escape 6 cyl Four Wheel Drive Automatic 124000 miles

Bought car for my son from car dealer. Immediately following transaction, check engine light went on. Had them diagnose. Two codes. Had a misfire (cylinder 5) and a O2 sensor fault (Bank 1 Sensor 2). Fixed the cylinder with new injector, coil and plug. Car ran MUCH better. However, got the O2 fault again. Found worn wire on sensor, so replaced. Got same fault again. Checked up and downstream voltages. Good. Shows cat is working. No leaks found, no other codes. Any ideas of how to clear this code as we can't pass inspection.

obxautomedic · Posted at Wed Nov 04, 2009 9:06 am

Hello,

Did you replace the Sensor or just the one wire? If just replace the wire then you need to replace the Sensor. The shorted wire shorted the sensor.

If you did replace the sensor check fuse F1.5 in the under hood fuse block.

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Hugh Streep · Posted at Fri Nov 06, 2009 7:12 am

O2 Sensor was replaced. Actually replaced both downstream sensors (four total, two per bank). Assume they are working as able to pull measured voltages off them. Not sure which fuse under the hood is F1.5. What size is it and what function would it be labeled under? Looked and none labeled as "F1.5". Pulled and checked all of the smaller fuses and all okay. Other ideas?

Hugh Streep · Posted at Fri Nov 06, 2009 1:09 pm

Here is the link to the owner's manual.

http://www.motorcraftservice.com/pubs/content/~WO3204/~MUS~LEN/34/03204og4e.pdf

Page 150 is where fuse information starts. Please let me know where to check. Thanks!

obxautomedic · Posted at Fri Nov 06, 2009 5:50 pm

Hi Hugh,

Sorry tried to respond earlier but I am work my fulltime job as an EMT. And been little busy today.

Anyway, I can post a pic tomorrow when I get home. I don't have access to my Mitchell1 from here. And your link won't let me in.

In newer vehicle the O2 sensors are now Heated and require a power source to heat them so there is a fuse in the curcuit. If the fuse blows it will set a code for and O2 Sensor. It should show in your owners manual and the repair manual as Heated O2 Sensor.

Question - on the part numbers of the sensors. Were they all the same part number? If so that may be your problem if you purchased the OEM Sensors. The passenger before cat sensor shows as a different part number than the other 3. If you purchased the Universal Sensors then you may want to recheck the wiring.

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Hugh Streep · Posted at Sat Nov 07, 2009 7:07 am

Installed Bosch on downstream sensors only. Bought at Pep Boys. Part # 15719. See: http://c2c.activant.com/ctoc/index.jsp?ID=aEz1rACw.Pnx6LFN9CU8KeWBCUBp3AlMIXj0A

Are you suggesting changing upstream as well with the same kind?

obxautomedic · Posted at Sat Nov 07, 2009 12:01 pm

OK, you might want to call your local parts store and have them look it up again. The Part Number I come up with is 15718.

Also here is the diagram for the fuse....

Also here are the OE Part #'s you can give them to the parts store and have then cross them over.

After Cat driver side = YL8Z 9G444 AC
After Cat passenger side = 5L8Z 9G444 A

The before cat are both the same #

Before Cat drivers side = YL8Z 9F472 AA
Before Cat Passenger Side = YL8Z 9F472 AA

If you are getting the same code as you did when you initially changed the sensor then no I would change out the upstream ones till figure out whats going on with Bank 1 Sensor 2.

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Hugh Streep · Posted at Sat Nov 07, 2009 2:37 pm

Fuse is good. You are correct that the first choice would be 15718. They did not have the first time, so went with 15719 which is same only longer wires, so it can be used on either left or right or one of the upstream. When we changed Bank 2 downstream sensor, I actually did get the 15718. But that one did not even need to be changed. We just did it because that was the side that had the misfiring cylinder (#5). But no sensor fault code on that side. Anyway, I believe the 15719 should be fine and we are still getting P0136 which is Bank 1 Sensor 2. Checked for leak, and nothing. Mechanic wants to change Cat, which we don't want to do if it is good and voltage readings indicate it is working. I may give to Ford and let them try and figure it out. By the way, I am a volunteer EMT, so I appreciate your service and help.

obxautomedic · Posted at Sat Nov 07, 2009 6:52 pm

Ok, and you don't have the Misfire Code right?

Also other than the sensor code there are no other drivability problems. If no other problems then I would say Cat is fine.

If there is some drivability problems then one way to check Cat is to remove an O2 sensor and drive the vehicle to see if problem improves or not. If does then of course the cat is failing and should be replaced.

Now, it doesn't happen often but it does happen. You may have gotten a New Bad Sensor. If you still have the old one that wasn't burnt, try put it in the place of the new one in the problem bank.

Then clear code with code scanner.

As EMT's were are all appreciated just pretty much by our pt's and there families more than employer, at least thats how it is here.

Love my Job hate the Politics.

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Hugh Streep · Posted at Sun Nov 08, 2009 5:11 am

Originally we did have the misfire code for cylinder #5, but when we replace coil and injector, it fixed the problem and cleared and car ran better. So no more issues there and that is actually on Bank 2 of this car.

As for the downstream sensors, help me out. I thought all they did was monitor. That is, they don't change rich/lean fuel output and therefore don't affect performance. And I was told cat only cleans emissions, so it too will not affect performance. Downstream O2 Sensor's (monitor) job is to measure downstream output and compare to upstream sensor to confirm cat is doing its job. In our case, we show it is working. Was I told all this correctly? If so, then perhaps we have no real problem except maybe the computer. I will try switching sensors to see if that clears.

I hear you about the politics. It is even worse on volunteers who do it for all the right reasons and still are treated poorly. Same everywhere I am afraid and we are losing more and more members due to it. Probably will end up going with paid (professional) in our town before you know it. Oh well.