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Discussion Starter · #1 ·
P1131 Bank 1 Sensor 1 bad, how to replace?

How do you replace this O2 sensor? I saw where it goes into the exhaust manifold, but I can't see the other end of it, where the harness plugs in. I did a check and got 1131, so I'm guessing I have to replace this sensor.

Mike


EDIT: I replaced the first sensor at Bank 1, and reset the computer. As soon as I went driving for a few minutes, the CEL came on again, and I'm now getting P0155 and P1151, which basically say the first sensor at Bank 2 is malfunctioning. What's goin on here?

Mike
 

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RE:p1131 Bank 1 Sensor 1 bad, how to replace?

is that on the front or back manifold? I only have 2 sensors (newer coug) but i know the front connects by the belt underneath and to the right of the imrc cover. the rear manifold is on the back left of the manifold. They're green connectors, i'm assuming that would be the same for all years.
 

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Discussion Starter · #3 ·
RE:p1131 Bank 1 Sensor 1 bad, how to replace?

it's the manifold closest to the firewall. When looking at the sensor from the bottom, I can see the wires are near the thick red alternator wire, and they go up towards the top of the engine, but I can't see to where. And looking at it from above, the harness is nowhere to be seen.

Mike
 

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RE: P1131 Bank 1 Sensor 1 bad, how to replace?

The upper O2 harness should be attached to the main enclosed wire harness, next to the mega fuse. Kinda of a PIA to get to! And yes I believe they are green...

Greg
 

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Discussion Starter · #6 ·
RE:p1131 Bank 1 Sensor 1 bad, how to replace?

wow those are great pics! Thanks Chris. I'm gonna take a look right now.

Mike
 

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RE: P1131 Bank 1 Sensor 1 bad, how to replace?

hehehe..the harness isn't the part you have to worry about. :biggrin:
 

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Discussion Starter · #8 ·
RE:p1131 Bank 1 Sensor 1 bad, how to replace?

Originally posted by: LostRacer
hehehe..the harness isn't the part you have to worry about. :biggrin:
yea really I just looked at it. What's the best way to get at the sensor, from the bottom, or from the top? I'm thinking of removing the coil pack to see if I can get at it that way. What do you think?

Mike
 

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RE:p1131 Bank 1 Sensor 1 bad, how to replace?

thats how i removed my sensor. with a big wrench from the top. the bottom looks imposible. if u remove the coil pack then the main harness bolts onto the manifold with 2 bolts. move the main harness outta the way and u can get ur hand in there. its a pita but only took me about 50 mins for both sensors. front and back. the lowers look easy.
 

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Discussion Starter · #10 ·
RE:EDIT: Replaced sensor for P1131 now getting P0155 and P1151???

I replaced the first sensor at Bank 1 to clear the P1131 error code, and reset the computer. As soon as I went driving for a few minutes, the CEL came on again, and I'm now getting P0155 and P1151, which basically say the first sensor at Bank 2 is malfunctioning. What's goin on here?

Mike
 

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RE: EDIT: Replaced sensor for P1131 now getting P0155 and P1151???

Did you have the codes cleared or did you just pull the battery? If you just pulled the battery cable go have your codes cleared and try it out. If you're still getting the error make sure the sensor is in good.
 

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Discussion Starter · #12 ·
RE:EDIT: Replaced sensor for P1131 now getting P0155 and P1151???

I have an OBDII scanner that checks and clears CEL codes. So after I changed the first sensor, I plugged in the scanner and let it clear the codes. Then, later that night the CEL came on again and I got these two new codes. I already bought another O2 sensor for Bank 2, so we'll see if that fixes it.

Mike
 

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Discussion Starter · #13 ·
RE:EDIT: Replaced sensor for P1131 now getting P0155 and P1151???

oh man I just replaced the sensor in the front manifold and I'm still getting 0155 and 1151 :banghead:

Mike
 

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RE:EDIT: Replaced sensor for P1131 now getting P0155 and P1151???

Clearing the codes with a code reader will NOT reset your computer.. You will need to pull battery connection, step on brake pedal (this discharges stored voltage on line), RECONNECT BATTERY. Now you should be okay. If that was your real problem.
 

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Discussion Starter · #15 ·
RE:EDIT: Replaced sensor for P1131 now getting P0155 and P1151???

shouldn't the CEL go away anyway if everything is fixed, after a few drive cycles?

Mike
 

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RE:EDIT: Replaced sensor for P1131 now getting P0155 and P1151???

Originally posted by: MrFroge
Clearing the codes with a code reader will NOT reset your computer.. You will need to pull battery connection, step on brake pedal (this discharges stored voltage on line), RECONNECT BATTERY. Now you should be okay. If that was your real problem.
There is no need to reset the PCM unless you modified the car and you want the PCM to learn the new mod quickly. As far as DTCs and the PCM, disconnecting the battery does nothing. It will remove the last key cycle code, but it will not remove any stored codes.....which are what triggers the CEL.

If you removed all DTCs from your PCM with a scanner and they came back, then you didn't fix the problem...or another problem now exists. Disconnecting the battery will not help.
 

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RE:EDIT: Replaced sensor for P1131 now getting P0155 and P1151???

From the Ford Maintenance manual:

The OBD II system monitors virtually all emission control systems and components that can affect tailpipe or evaporative emissions. In most cases, malfunctions must be detected before emissions exceed 1.5 times the applicable 50K- or 100K-mile emission standards. If a system or component exceeds emission thresholds or fails to operate within a manufacturer's specifications, a DTC will be stored and the MIL will be illuminated within two driving cycles.

The OBD II system monitors for malfunctions either continuously, regardless of driving mode, or non-continuously, once per drive cycle during specific drive modes. A DTC is stored in the PCM Keep Alive Memory (KAM) when a malfunction is initially detected. In most cases the MIL is illuminated after two consecutive drive cycles with the malfunction present. Once the MIL is illuminated, three consecutive drive cycles without a malfunction detected are required to extinguish the MIL. The DTC is erased after 40 engine warm-up cycles once the MIL is extinguished.

I think it is a good idea to reset the system when ever you are making changes to the harware:

Idle Air Trim

Idle Air Trim is designed to adjust the Idle Air Control (IAC) calibration to correct for wear and aging of components. When engine conditions meet the learning requirement, the strategy monitors the engine and determines the values required for ideal idle calibration. The Idle Air Trim values are stored in a table for reference. This table is used by the PCM as a correction factor when controlling idle speed. The table is stored in Keep Alive Random Access Memory (RAM) and retains the learned values even after the engine is shut off. A Diagnostic Trouble Code (DTC) is output to indicate that the Idle Air Trim has reached its learning limits.

Whenever an IAC component is replaced or cleaned or a service affecting idle is performed, it is recommended that Keep Alive RAM be cleared. This is necessary so the idle strategy does not use the previously learned Idle Air Trim values.

To clear Keep Alive RAM, refer to PCM Reset in «Section 2». It is important to note that erasing DTCs with a scan tool does not reset the Idle Air Trim table.

Once Keep Alive RAM has been reset, the engine must idle for 15 minutes (actual time varies between strategies) to learn new idle air trim values. Idle quality will improve as the strategy adapts. Adaptation occurs in four separate modes. The modes are shown in the following table.
 

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Discussion Starter · #20 ·
Ok both O2 sensors up top (bank 1 and 2 in the manifolds) have been replaced. And I'm still getting P1151 and P0155, which indicate something with Bank 2 sensor 1. I even swapped both sensors to see if one might be bad, but I'm still getting the same code. What could the problem be?

Mike
 
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