Check Engine Light

[ledzilla]

My check engine light came on the other day. I went over to the local Autozone and had them check the codes. This is what I got:

Code P1151

Definition -- Lack of O2 switches - Bank 2 Sensor 1

Explanation -- ECM could not adjust fuel trim because of a lean or rich condition

Probable Causes --
1) Fuel pressure high or low
2) MAF sensor dirty/defective
3) Vacuum leak on engine
4) Leaking fuel injector or fuel pressure regulator

I'm sure it's not #2, since there was an improvement after I cleaned the MAFS. I'm also sure it isn't #4 since I don't smell any gas (I've had a fuel leak on my old Lincoln, so I know the situation). If anyone knows what else could be done, it would be a great help. BTW, when the light first came on there was no difference in the way the car behaved. After a few days, though, I seem to be getting a rough idle and some surging (?) when accelerating (not WOT).

[Zack]

Clear the code, fill up with Amoco premium, go beat the snot out of it.

[Black_Noise]

it sounds like the 02 sensor is bad

[Local Boy]

Fuel filter? Have you changed yours yet?

Good Luck...

ALOHA

[ledzilla]

New fuel filter (installed Sat) and clean MAF sensor (also Sat). Been using Amoco Ultimate since I bought the car. Only other gas used is Shell V-Power. I'll check out costs for O2 sensors. Not thrilled by that prospect, though.

[chader]

New fuel filter (installed Sat) and clean MAF sensor (also Sat). Been using Amoco Ultimate since I bought the car. Only other gas used is Shell V-Power. I'll check out costs for O2 sensors. Not thrilled by that prospect, though.

Did the mil come on after you cleaned the MAF?

[ledzilla]

No, the light came on several days before cleaning it. I was hoping that the new filter and the cleaning would clear it out, but I was wrong.

[magindat]

No, the light came on several days before cleaning it. I was hoping that the new filter and the cleaning would clear it out, but I was wrong.

You need to clear it and see if the problem persists to throw it again.

[ledzilla]

How do you clear it?

[Dragcity]

To clear it you must hit the "Maximum Speed Achieved" Function, which is programmed in the EEC. Only one way to do that.

Only Kidding!

Disconnect battery terminals (Clean and dialectric grease while you are at it). Leave off for about 20 minutes. I usually clean the Throttle body, linkage and MAF while I wait. Wipe down the fender wells and plastic shrouds with silicone, clean things up, check all fluids....

Re-attach the terminal connectors. Start engine wihtout any accessories runing. Let her warm to normal op temp. Take her for a spin. See what you get. Codes may or may not come back.

[ledzilla]

I already activated that function on I-88... hehehe

Thanks for the info. I feel that was something I should've known already. I did the reset and the beast is out in the company lot warming up right now (yes, I have tools in the trunk... always have tools in the trunk). I suppose we'll see how it goes by time I get home.

[Blackened300a]

It may take a few miles and keyturns to really make sure that the code doesnt come back. Sometimes it may even take up to a hundred miles of driving to be sure the code is cleared.
When you said the idle surged, did you check all your intake tube clamps? Also make sure your connections on your MAF are clean and plugged in tight.

[Pat]

Auto Zone should be able to clear the code. Ask 'em.

[thePunisher]

a maf problem would not cause a bank specific lean or rich problem....if maf were faulty both banks would have similar issues..same rule goes for fuel filters, pumps etc....the likely cause here is an o2 senser that intermittenly stops switching...it is most likely worn/damaged. i see this all the time at the dealer. as stated above you dont need the parts store to clear the code. just disconnect the battery for a few minutes.....this will clear the code and the KAM (keep alive memory)

[ledzilla]

Ok. I did a battery disconnect after cleaning the MAF sensor. The light came back on after driving about 4 or 5 miles. That evening I replaced the fuel filter, but I didn't disconnect the battery again until around the time I got off of work. I went a few more miles and ran the motor for a while longer this time and the light hasn't come back on. I'm not assuming that the problem is solved, so I'll keep an eye on it. If it truly is a faulty O2 sensor, can you tell me which one it is based on the code description? Or would I be better off replacing both sensors?

BTW, I was checking out O2 sensors online to get an idea of the cost. Any recommendations on manufacturers, or just go with Motorcraft?