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P1151 on a V6

A

annacon

CEG'er
Joined
Apr 9, 2009
Messages
33
Hello, first post here. A brief rundown of the Contour:
140+K miles, car runs excellent. I just finished repairing the EGR system including new EGR valve, pressure differential sensor, replaced the vacuum lines on the sensor and removing the throttle body and cleaning the EGR ports. I believe cleaning the ports would have been the only job necessary to clear the code I was getting for the EGR system but I am new to the car and it is going to my daughter so while my hands were dirty I did everything my OCD told me to do.
Now my current code problem:
I ran the car for about 100 miles and CEL came on and I pulled the code and got "P1151-manufacturer controlled fuel and air metering". I/M monitors show all applicable systems ready except "EVAP". Reseaching here and elsewhere tells me to replace the the 02 sensor which I will do.
My question:
Can these two problems be related or are they independent of one another?
Through all of this I must repeat that the car runs great showing no signs of a vacuum leak.
Thank you, Keith
 
[FONT=arial,verdana,helvetica,sans-serif]P1151[/FONT][FONT=arial,verdana,helvetica,sans-serif]Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 2. [/FONT]

might be time for a new O2 sensor. but check for vacuum leaks first on bank 2.

also might suggest a intake cleaning along with replaceing the intake gaskets, then see what happens to this code.
 
BrApple, thanks for the advice. I will spray the mating area of the intake with carb cleaner to see if a change in idle occurs. I have quite a few years of mechanic work and the car shows no sign of a vacuum leak. Smooth idle, no stumble on throttle application etc. Will a vacuum leak manifest itself as such or is this engine different? I see a lot of advice on vacuum leaks and they have always been obvious to me. Am I missing something? Any advice on the I/M monitor for the EVAP showing "not ready"? Thank you, Keith
 
BrApple, went out and warmed the car up and sprayed around mating surfaces of the intake and had no change in engine sound or rpm. I am leaning toward O2 sensor. I just ordered one from Rock Auto. I will post back with results. Again, thanks; Keith
 
Update:
Installed new O2 sensor (easy job) and cleared the codes with my scanner. I drove the car about 5 miles and the CEL came on. Pulled the code and it was the P1151 again. I cleared that just for S&G's and drove the car and it took about 25 miles for the CEL to come on again. Pulled the codes and got a P1151 and a P0155. I feel like I am chasing a moving target. For reference I install a Bosch O2 sensor that had the OEM plug (no cut and splice). I am using an Actron CP9135 to retrieve the codes. Thanks, Keith
 
Those intake manifold gaskets are REALLY hard to check by just blindly spraying stuff at them. There is a gasket between the upper and lower, and a gasket between the lower and the cylinder head. Both are surrounded by LOTS of twisted aluminum, so I doubt you covered every square inch of surface area.

In addition, the leak may be MINUTELY small, and a spray would not change the idle appreciably. The MAF sensors are VERY precise, and throw lean codes very easily.

Judging from your high miles, I would replace the intake manifold gaskets, upper AND lower, on general principle; and I wouldn't be surprised if it alleviates your lean code as well.

Bank 2 is, of course, the front of the car. The fact that your code is only pointing to one bank, and the O2 sensor didn't fix it, pretty much leaves ONLY the gasket as the logical point of failure.
 
Any clue as to why after a cleaning of the EGR port at the mating surface of the TB and Intake manifold I would get this code/codes? I was very careful to clean all surfaces. For what it's worth i didn't "blindly spray stuff". I directed the spray of carb cleaner toward the mating surfaces of the intake manifold. With that said I will give the intake gaskets a shot. There are upper and lower correct? I should do both? Thanks, Keith
 
Hard to say exactly, but you DID have lots of pieces off that are sealed with a gasket (EGR valve, throttle body; did you replace both gaskets, or re-use?). And like I said, the MAF is really picky and histrionic about its readings.

And I said "blindly" not because you weren't careful, but because you really cannot see most of the surface area down there without taking it all apart.

And yes, the gaskets are both upper and lower, and should be about $15 a set at your local auto parts store.

The lowers are a little tricky, because you really need to disconnect the fuel line to get the fuel rail/injectors out of the way (you can't just pull them aside, because they run right under the IMRC linkage). The auto parts store also sells a cheap set of fuel line quick-disconnect tools to do that.
 
FWIW, you CANNOT hear a change in the idle when spraying in a quaest for leaks. The computer is too fast and compensates before any audible difference can take place.

I've found that the only way to do this is to watch the short-term fuel trims on my scanner while spraying then looking for a sudden spike.
 
Thanks, Andy, the parts that I removed and replaced were installed with new gaskets. A lesson in "false economy" I learned the hard way long ago;
don't reuse a $2 gasket. I am understanding from your knowledge that the engine is getting air that the MAF isn't reading. As I was working in that area I will give my work a thorough going over to be sure I didn't put a tear in the bellows or the hoses leading into it. Are the intake gaskets as common a weak spot as they are said to be? It seems like a default answer to a lot of problems. I don't want to get into a "house that Jack built" situation with this problem. Thanks again for your help, Keith
 
if you got P0155 again it means that the o2 sensor your replaced has a fault

"P0155 Upstream Heated Oxygen Sensor circuit fault - Bank No. 2."
 
Bad sensor? Maybe I'll put the old one back in and see if the P0155 comes back. Easy enough to do. Thanks, Keith
 
annacon said:
Bad sensor? Maybe I'll put the old one back in and see if the P0155 comes back. Easy enough to do. Thanks, Keith
Click to expand...

Another option is to switch sides with the front and rear sensors, and see if the code comes back on the other side, or the same side.
 
Update on the O2 codes: My gut feeling was that the problem was limited to the O2 and not the intake because the code only appeared after I cleaned the EGR passage at the throttle body. I felt I must have been the cause of the problem and with that feeling I went over every step of my EGR repair. I changed any vacuum hose that was touched or moved in the process of the repair. I then disconnected the O2 sensor and reconnected it to be sure the connection was tight. The second time around I heard an appreciable "click" at the connector, something I don't recall hearing the first time. I cleared the codes and ran the car through an extended drive cycle and the CEL stayed off. Upon returning home I scanned for any codes or pending codes and all was clear. As careful as I thought I was the first time I feel I could have been more thorough. Lesson learned. I have not yet seen the EVAP show ready through all of this and I am wondering if there is a way of getting it to show ready. I will start another thread on the EVAP topic and see what comes up. Lastly I owe a big thank you to the people who took the time to post a response to my questions. Thank you, Keith
 
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