Originally posted by HITMANinMI:
UPDATE:

Went to a different Autozone one I always go to. The guy says he doubts the sensor is bad so early only 17k on the new sensor, plus he said he was pretty sure I would get a code for it if it was bad.
So I said I'll clean the MAf first, he said it may not do much but I came home and did it anyways.

He says the first thing he would do is clean the EGR valve. So got some carb. cleaner now if I only I knew where it was?

Also I checked all vacuum lines and they are in good shape no cracks or anything.





Ok, here ya go... I'll throw you a bone since noone else will.

From the 98 Ford Service Manual -


Diagnostic Trouble Codes (DTCs) P0171 bank 1 (Cylinder 1) indicate the fuel/air ratio is too lean. The fuel trim system is at the rich correction limit.

DTCs HO2S Reference list:

-- HO2S-11 = DTCs P0171 and P0172

-- HO2S-21 = DTCs P0174 and P0175

"HO2S-11", in the last statment there means, Heated 02 Oxygen Sensor - Bank 1 Cylinder1


Possible causes:

Fuel system

-- Excessive fuel pressure.

-- Leaking fuel injector(s).

-- Leaking fuel pressure regulator.

-- Low fuel pressure or running out of fuel.

-- Contaminated fuel injector(s).

-- Vapor management valve (VMV) leaking.

Induction system

-- Air leaks after the MAF.

-- Vacuum leaks (vacuum lines and gaskets).

-- Restricted air inlet.

-- PCV system.

-- Fuel purge system.

-- Improperly seated engine oil dipstick.

EGR System

-- leaking gasket.

-- Stuck open EGR valve.

-- Leaking diaphragm.

Base engine

-- Oil overfill.

-- Cam timing.

-- Cylinder compression.

-- Exhaust leaks before or near the HO2S(s).

* Check intake air system for leaks, obstructions and damage.

* Check air cleaner element, air cleaner housing for blockage.

* Verify integrity of the PCV system.

* Check for vacuum leaks.

* Are any of the above concerns present?

Yes
REPAIR as necessary. COMPLETE PCM Reset to clear DTCs. RERUN «Quick Test».

No
GO to Pinpoint Test Step «DC25». If MAF reading is within specification, return to Pinpoint Test Step «H42».



Phillip Jackson `98 Mystique LS 262K+ and counting... ATX rebuilt @ 151K "This storm has broken me, my only friend!" RIP Dime