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Discussion Starter · #1 ·
Hey guys, hoping you can help me out with a small issue I've got.

CEL came on a little while ago and I checked the code. p0141

The code is a problem with the downstream o2 sensor. So I went to autozone and picked up the part for a whopping $135

When I started the process to take out the o2 sensor I saw that it was unplugged under the passenger's seat!?!? I don't know how this happened, as far as I know the part has never been replaced before.

Anyways, I reconnected the sensor, hooked up the battery and the CEL came on again when I started the car. I checked the code again and P0141 was still there.

I drove the car around for a while (36 miles) and the light never went off.

So should I just go ahead and replace the part? Or is there anything else I should check? I find it hard to believe that the part both failed and magically came unplugged, but with my luck anything is possible :D

Any advice is appreciated. Thanks!
 

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How long was the battery disconnected?

Basically , downstream o2 sensors measure the efficiency of the catalytic converter , while the upstream is primarily responsible for proper A/F ratio.

Aftermarket o2 sensors are prone to not be read correctly , common issue. Suck it up and go OEM. I found this the hard way on both of my old Honda's , CEL would just go back in with aftermarket sensors. I slapped in an OEM one and I was golden.
 

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unplug the positive terminal on battery or take to a auto parts place to have the computer reset?
 
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Discussion Starter · #4 ·
How long was the battery disconnected?

Basically , downstream o2 sensors measure the efficiency of the catalytic converter , while the upstream is primarily responsible for proper A/F ratio.

Aftermarket o2 sensors are prone to not be read correctly , common issue. Suck it up and go OEM. I found this the hard way on both of my old Honda's , CEL would just go back in with aftermarket sensors. I slapped in an OEM one and I was golden.
Battery was disconnected for roughly 10-15 minutes.

Thanks for the info about the aftermarket sensors. The one I purchased hasn't even been taken out of the box yet, so I'll return that and pick up an OEM sensor.

unplug the positive terminal on battery or take to a auto parts place to have the computer reset?
How is the computer reset? Do I need to disconnect the battery for a certain length of time?
The guy who checked the code told me that I would have to drive around a little before the computer would reset itself.

Sorry for my complete lack of knowledge. I just learn things as I go.
 

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If that O2 sensor was unplugged it could have been part of troubleshooting the issue and someone forgot to plug it back in. The P0141 code says the Heater is not working on the O2 sensor, But I would also expect to see a P0136 error as well if the sensor was unplugged. The Heater is controlled by the computer and power is always applied to the heater, but the ground is how the computer controls the heater on and off. There is a fuse that protects the Heater as well, so you should check to see if you have voltage on the heater wire (there are 4 wires to the sensor), if there is no voltage on the +heater then you need to look at the wiring and the fuse.

1. + heater
2. - heater
3. Signal
4. 12V



The codes can be cleared from the computer many ways
1. disconnect the battery cable(s)
2. Remove the Fuse for the Computer
3. Reset with a code reader

Once the codes have been cleared the computer has to run what is known as Readiness tests, those happen during a "drive cycle".

To tell if the readniness test have completed without a scan tool:

Turn the ignition switch to the ON (II) position, without starting the engine. The MIL will come on for 20 seconds. If it then goes off, the readiness monitors are set. If it blinks five times, the readiness monitors are not set.

A drive cycle for Honda is the following

1. Make sure the gas tank is nearly, but not completely, full (around 3/4).
2. Make sure the vehicle has been parked with the engine off for 6 hours or more.
3. Make sure the ambient temperature is between 40° and 95°F.
4. Without touching the accelerator pedal, start the engine, and let it idle for 20 seconds.
5. Keep the vehicle in Park (automatic) or neutral (manual). Increase the engine speed to 2,000 rpm, and hold it there until the temperature gauge rises to at least 1/4 of the scale (about 3 minutes).
6. Without touching the accelerator pedal, let the engine idle for 20 seconds.
7. Select a nearby lightly traveled major highway where you can maintain a speed of 50 to 60 mph for at least 20 minutes. Drive on the highway in D (automatic) or 5th (manual). Do not use the cruise control. When traffic allows, drive for 90 seconds without moving the accelerator pedal. (Vehicle speed may vary slightly; this is okay.) If you cannot do this for a continuous 90 seconds because of traffic conditions, drive for at least 30 seconds, then repeat it two more times (for a total of 90 seconds).
8. Then drive in city/suburban traffic for at least 10 minutes. When traffic conditions allow, let the vehicle coast for several seconds without using the accelerator pedal or the brake pedal.
9. Make sure the vehicle has been parked with the engine off for 30 minutes.

Or Drive the car normally for 2 or 3 days and they will normally complete.
 
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