my 2002 keeps throwing the same codes p1131 and p1151. because I have not had the truck too long the dealer must guarantee it passes inspection so I have been having it fixed by them at no charge. It went in the other day and they claim to have fixed the issue by replacing an o2 sensor in bank 1. I think because I didnt have to pay they just cleared the code in anticipation that I would go to inspection before the code would come back and they wouldnt be liable for the fix. However, if that was their intention, I thwarted their efforts to avoid paying for the part and just clearing the code. Now, I would like to know how to actually go about solving this issue because I have a good feeling the next time around at the dealer they are going to clear the code and pay to have the vehicle inspected privately and push the truck through inspection. I came across this link and would like some opinions on whether this could solve the issue or not. Please let me know what you think.
http://autotechrepair.suite101.com/a...r_flow_sensors

 

Here is what the factory PCED lists as possible causes:

Electrical:
Short to VPWR in harness or HO2S
Water in harness connector
Open/Shorted HO2S circuit
Corrosion or poor mating terminals and wiring
Damaged HO2S
Damaged PCM
Fuel System:
Excessive fuel pressure
Leaking/contaminated fuel injectors
Leaking fuel pressure regulator
Low fuel pressure or running out of fuel
Vapor recovery system
Induction System:
Air leaks after the MAF
Vacuum Leaks
PCV system
Improperly seated engine oil dipstick
EGR System:
Leaking gasket
Stuck EGR valve
Leaking diaphragm or EVR
Base Engine:
Oil overfill
Cam timing
Cylinder compression
Exhaust leaks before or near the HO2S(s)

 

Your up against not knowing what the codes are telling about the fault and a dealer that is not making or does not know how to make serious attempts to find the cause due to "profit" concerns, instead of standing behind the sale.
Both codes are telling the same thing so it's not two different problems.
What you have is a system that is running rich on fuel.
The OX sensors are seeing this and trying to lean out the fuel table in an attempt to self adjust for the excess fuel.
The sensors do a continious hunting called switching. Presently they are not switching as indicated by the codes.
Removing the connectors off the sensors would have the same effect of switching not being detected. If this were done on a trouble free motor, the motor automatically will go rich to protect the motor from more servere effects of running lean.
The system has the built-in ability to shift like this for componant aging and a number of other reasons.
When the shift goes out of limits, the code/s is set indicating it's time for a repair to be done.
It's not the OX sensors. They are only reporting the system fault as the only means you know there is an issue.
Why an engine will run rich is to be determined.
Excess "unaccounted-for" air getting in the intake, leaking fuel injectors, fuel pressure to high etc.
Any common sense reason the 'fueling' ends up being to rich.
There you have the ground work behind your issue, now get someone to work on the issue with intelligence and pay them for there work, force a warrenty repair, or run with it and you will be fine.

I would not be above printing this out and showing the dealer what the deal is if they don't know what to do about THEIR WARRENTY.
If it's not repaired now, you will be stuck again in another year as well as have a CEL light on the whole time and running a gas hog from the excess richness.
If this geos on too long, it can have a very negitive effect on CAT life and they are quite expensive to replace.
Good luck.

 

Guys, thank you for the insight. I have the truck at the dealer now for round 2. If the problem is not solved this time I will push a warranty issue with them regarding it. I would like to give them the chance to correct the issue without being a d'bag towards them. However if it gets to that point I will. I will report back with their resolution later today.

 

sorry to bring back the dead but are you serious is there a simple in order list, say most likely to least likely? link please, thanks

 

Trouble Code: P1131 (undefined)
Lack of HO2S-11 Switching, HO2S Signal Low Input
Number of Trips to Set Code: 2

OBD II Monitor Type: CCM
Indicators: MIL

Trouble Code Conditions:
DTC P0300-P0310 not set, engine started, engine running in closed loop, and the PCM detected the HO2S-11 was not switching (i.e., the HO2S-11 indicated a lean A/F mixture).

Possible Causes:

■Air intake system leaking, vacuum hoses leaking or damaged
■Air leaks located after the MAF sensor mounting location
■Base engine mechanical fault (i.e., compression, valve timing)
■HO2S circuits wet or oily, corroded, or poor terminal contact
■HO2S signal circuit open, shorted to ground, shorted to power, or the sensor has failed
■Low fuel pressure or vehicle driven until it was out of fuel
■Possible air leaks at the PCV valve or at the related hoses



Trouble Code: P1151 (undefined)
Lack of HO2S-21 Switching, HO2S Signal Low Input
Number of Trips to Set Code: 2

OBD II Monitor Type: CCM
Indicators: MIL

Trouble Code Conditions:
DTC P0300-P0310 not set, engine started, engine running in closed loop, and the PCM detected the HO2S-21 was not switching (i.e., the HO2S-21 indicated a lean A/F mixture).

Possible Causes:

■Air intake system leaking, vacuum hoses leaking or damaged
■Air leaks located after the MAF sensor mounting location or in the PCV system
■Base engine mechanical fault (i.e., compression, valve timing)
■HO2S circuits wet or oily, corroded, or poor terminal contact
■HO2S signal circuit open, shorted to ground, shorted to power, or the sensor has failed
■Low fuel pressure or vehicle driven until it was out of fuel

 

I think I would start with the easiest and cheapest thing on the list of possible causes and inspect/replace the gas cap lol.

 

thanks for the info, and yes the gas cap feels like it should be tight but its not. i put a used one on and it feels the same. should there be noticeable psi when removing the cap, say when fueling it up and such??? i am going to clean the maf sensor today and see if it will stay away.

 

I've never had pressure come out of my system

 

Gas tanks work with a vaccum pulled through the EVAP system.
They are supposed to be a sealed system after the cap is put on.
The cap does not have to be a tight 'feel' for fit to be good.
The system has pressure monitors to tell you when there is a failure to draw a vacuume.
Codes are set for failures.

 

The gas cap has absolutely nothing to do with the codes in this thread. Do you see "gas cap" in the list I posted last year?


Ask the factory, that list is theirs.