P1151 and P0172, please help!

[RCameron]

Hi, my car is coding P1151 and P0172.
It's a 1998 Contour SE, V6, only about 60,000 miles on it, I bought it brand new in 1998. Never had a problem with it. I did have a very expensive remote starter installed about 2003.
When my dad hooked it up to retrieve the codes, and the CEL was turned off; my car runs awesome. Runs like the happiest engine ever. Idles perfectly.
When the CEL comes back on (next day or so) it starts running like crap: sluggish on the acceleration, idle seems to fluctuate.
After reading about these codes here on the forum, they seem at odds with one another; one "sytem too rich", one "too lean".
There doesn't seem to be any leaks, broken hoses, etc.
Would I be safe in assuming O2 sensors are faulty?
What should I do?
Thanks, R Cameron
http://www.contour.org/ceg-vb/showpost.php?p=58362&postcount=2

 

[Tony2005]

Welcome . Start by cleaning the MAF sensor.

From TSB,
P0172 - System Too Rich (Bank 1)
The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The code sets when the adaptive fuel tables reach a lean calibrated limit.

Fuel System:
· Excessive fuel pressure
· Leaking/contaminated fuel injectors
· Vapor recovery system concern
Base Engine:
· Oil overfill
· Cam timing concern
· Low cylinder compression
· Excessive engine wear
Powertrain Control System:
· PCM concern
Induction System:
· MAF contamination

P1151 - Lack of HO2S-21 Switch, Bank 2 Upper Sensor
Fuel Trim at LimitThe HEGO Sensor is monitored for switching. The code will set when the HO2S fails to switch due to circuit or fuel at or exceeding a calibrated limit.
Electrical:
· Short to VPWR or VREF in harness or HO2S
· HO2S circuit shorted to Ground
· Water in harness connector
· Open circuit
· Corrosion or poor mating terminals and wiring
· Damaged HO2S
· Damaged PCM (other DTCs should be present)

Fuel System:
· Excessive fuel pressure (stuck fuel pressure regulator, restricted fuel return lines, etc.)
· Leaking/contaminated fuel injectors or fuel pressure regulator
· Low fuel pressure or running out of fuel (fuel pump concern, fuel supply line restrictions, low fuel level, etc.)
· Vapor recovery system (stuck VMV, etc.)

Induction System:
· MAF contamination
· Air leaks between MAF and throttle plate
· PCV system / Other vacuum leaks
· Improperly seated engine oil dipstick

EGR System:
· Leaking gasket
· Stuck EGR valve / Leaking diaphragm or EVR

Base Engine:
· Oil overfill
· Incorrect cylinder compression
· Exhaust leaks before or near the HO2S
· Secondary air stuck on

Edit. Check for vacuum leaks by spraying with carb cleaner. If the idle changes, you found the leak.

Check for vacuum leaks at gaskets, hoses and hose clampes.

Clean the MAF sensor
http://www.contour.org/mods/mods.php?s=howto&displayid=36
and
http://www.contour.org/ubbthreads/showflat.php?Cat=&Board=zetecmaint&Number=989728&page=&view=&sb=5&o=&fpart=1&vc=1
and
http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/1b/cb/25/0900823d801bcb25.jsp

 

[SVT_22]

^ beat me too it but for future reference go here: http://www.v8sho.com/SHO/TSB0197HO2SServiceTips.htm