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P1151

W

waldick

CEG'er
Joined
Nov 3, 2007
Messages
164
Location
NW Ohio
ok, I've read most of the threads that contain the p1151 cel. My car is a '98 SE, Mtx, 2.5, 169K.

I just replaced the engine and don't know if this motor was throwing codes in the previous car. Anyway, it runs smooth, although the idle is a little slow in coming down, compared to previous 2.5s.

So after installing the motor i get the p1151 code. I checked for vacuum leaks by the carb cleaner method with no hint of a leak. I used up more than half a can of the spray stuff in the process.

I then changed out the upstream o2 sensor with one i had...p1151 after a few miles. Datastream gives me a reading on the sensor, although i don't know exactly how to interpret the voltage readings, other than they appear high, like closer to 1 volt than they should be, which would indicate sensor working properly and a lean reading, right ?


Then swapped out the MAF with one i had....p1151 after a few miles.

So now if i swap out upstream sensors and i still get p1151, i suppose i need to take a closer look at the UIM/LIM gaskets. I figure if the leak were somewhere else it would run both banks lean right ?

But if it is the gaskets, shouldn't the carb spray have had some effect? I sprayed it pretty liberally around the front bank.

How much of a leak will set off the sensor?


Any other ideas ?
 
Don't know about a six. Do know that lean is close to .1 volt, rich is maybe .9 volt, or close to one. A normal working sensor will quickly switch back and forth above and below .5 volt. Meaning like .1-.9-.2-.9-.1-.8, similar. A vacuum leak will stay close to .1 or .2 depending on how bad it is. It will also show much worse at idle and seem to get better as engine speeds up.
 
I'd like to see some answers as well, my car every like 7 or so months it will throw P0420, but last month my car threw P0420 and P1151, and then yesterday she threw P1151, usually stays away for awhile. It's not every other day after clearning the code it comes back.

My code scanner said lack of basically hot 02 in bank 2, sensor 1. Which I believe from what my brother told me was the sensor on the back side of the engine and the upper sensor...
 
P1151 is a pretty reliable indicator that your upstream front O2 sensor has gone lazy or got damaged in the work.

I'd just replace it based on experience and see what turns up.

Steve

Firewall-side upstream sensor will cause a P1131....
 
Ok, what if i put the original sensor on the other bank ? If it is bad, i should get both a p1151 and a p1131. If i still only get a p1151, then i know its not the sensor, but a vacuum leak or something else. This way i can avoid spending $50 for a new sensor unless i have to...:)

What has me perplexed about a possible vacuum leak is the lack of effect the carb cleaner test had.

Anyway, Ill swap out the firewall upstream sensor and see what happens.

I'll also hook the scanner back up and report the exact range of readings on both upstream sensors.
 
If you want to screw with the firewall side sensor, be my guest.

Only a noob who's never done it before would volunteer for such a PITA job....

Anyone who has done it before will go buy a new sensor and not dink with the PITA one unless they have to.

These codes are seldom due to vacuum leaks. Those cause different fault codes.

Steve
 
OK
speaking of the front upper O2 sensor, what's the best way to attack it? Looks to me from the bottom. And it looks like the oil filter is kinda in the way. I'm about to do this, so any advice would be appreciated from the experienced. As Jimi would say, "Are you experienced?"
 
projectSHO89 said:
If you want to screw with the firewall side sensor, be my guest.

Only a noob who's never done it before would volunteer for such a PITA job....

Anyone who has done it before will go buy a new sensor and not dink with the PITA one unless they have to.

These codes are seldom due to vacuum leaks. Those cause different fault codes.

Steve
Click to expand...


ok, i understand that, but, remember i replaced the front sensor already with one i had off another SE...i just wonder what the chances are of two sensors being bad, that's all.

...just trying to save $50+, if i can :shrug:

btw, can you get to it from underneath, i mean is it easier that way ? I did read the "how-to" on the from-the-top-method.
 
grossgo said:
OK
speaking of the front upper O2 sensor, what's the best way to attack it? Looks to me from the bottom. And it looks like the oil filter is kinda in the way. I'm about to do this, so any advice would be appreciated from the experienced. As Jimi would say, "Are you experienced?"
Click to expand...
Yes, for the Radiator side (Bank 2) upper O2 sensor, you will have more room if you remove the oil filter first.
 
Thanks Tony,
That's what it looked like to me. I have another question. Bosch p/n for the upper sensor. The guy at Napa gave me a 13115, but every thing I read points to a p/n 15717 for the upper one. Can anyone point me in the right direction before I take this thing back?
Thanks for the help guys and girls.
 
UPDATE

So today i decided to attach the scan tool and drive for a while and see what the datastream readings were.

The bank 2 sensor readings did not switch back and forth as fast and mostly at all as the others. The reading also was higher on the high side than the others, staying around .935 volts. It would come down when coasting though.

Now the strange part. While i was checking pending codes i also found a p0171 which is for the other bank ?!?!

Now i'm totally confused :confused:

What other tets can i run to determine the problem ?
 
waldick said:
...Now the strange part. While i was checking pending codes i also found a p0171 which is for the other bank ?!?!

Now i'm totally confused :confused:

What other tets can i run to determine the problem ?
Click to expand...
Change the Bank 2 O2 sensor first. Then see if this P0171 becomes a "hard" code. If it turns off, then don't worry about it for now.
 
P0171 = Bank #1 too lean (maf needs cleaning, O2 slow/faulty, vacuum leak, pcv problem, fuel filter, injector)

I just had this code and the largest culprit seemed to be the fuel filter. I would look into this as it's only $9 to replace and maybe 30 minutes of time too. Worst case scenario, you've got a new fuel filter.
 
ok, so i replaced the sensor and it was fine for about 75 miles and several starts and stops, but now it's throwing p0420 :shrug:
 
yeah, that's what i thought. I have all the parts to build them. I'll try that over the weekend if i can find the time. Other than the light coming on, am i right about it not effecting performance ?

Also, now when the engine warms up the imrc won't open. I have replaced the transistor on a previous 'tour, so that should not be a problem. Am i correct that the p0420 and the imrc thing are not related? :confused:

man, i have not had this many problems with my car in such a short time before...:shrug: good thing i don't have to pay someone to fix all this...:laugh:
 
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