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Failed Emissions?

Old Dec 4, 2004 | 10:44 PM
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N. Willey
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Failed Emissions?

I'm new to the forum and I did a little digging, but I didn't find an answer to my question.

I have a 1999 F-150 4x4 4.2L and it failed the emissions test. The trouble code that came up was PO 161 = O2 sensor heater circuit malfunction (bank no. 2 sensor no. 2)
I was told to replace the O2 sensor, but this didn't help. I had it re-tested at a parts store and the same code came up.

1) Is Bank #2 the drivers side?

2) What do I need to do?

Neil Willey
Tucson, Arizona
 
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Old Dec 4, 2004 | 11:59 PM
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Welcome to the forum.

Yes, bank 2 sensor 2 is the one on the drivers side behind the converters. (furthest away from the engine)
If it was the one that you replaced and it is still giving the same code after being reset, you might want to check the wiring to it.
 
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Old Dec 5, 2004 | 04:42 PM
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Thank You for your help! I now have a few more questions.

1) If I unhook the battery will it reset this trouble code (PO 161)?

2) If that does reset it - and the code still pops up what is the best way to test the wiring?

N. Willey
Tucson, AZ
 
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Old Dec 5, 2004 | 05:33 PM
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Yes you can reset it by unhooking the battery for at least 15min. If it comes back, then a visual inspection it a good place to start. Just follow it as far as you can and check for smashed or melted wires (too close to exhaust).
 
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Old Dec 5, 2004 | 05:34 PM
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From: Forest Hill MD
Originally Posted by N. Willey
1) If I unhook the battery will it reset this trouble code (PO 161)?
Yes if you leave it 10 to 15 minutes it will reset the computer, or if you have a AutoZone in your area they can reset it with the code reader. If the problem comes back it is not fixed yet.

Is the check engine light on?

Chris
 
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Old Dec 5, 2004 | 09:12 PM
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Thanks guys! The check engine light came back on, so I took it back to Auto Zone and the same trouble code came up. Then I checked the wires, and followed them back and saw no problems with the outer casing. Any other suggestions?

N. Willey
 
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Old Dec 5, 2004 | 11:04 PM
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Here is the next step. Swap the two rear O2 sensors from side to side. Reset the light and when it comes back on, scan it again. If you get the same code, then it is a wiring issue, if you get PO141 code, then the new sensor is bad.
 
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