Question about 1999 Mercury Cougar
Manufacturer control fuel air metering?
Lack of HO2S-11 Switch, Indicates Lean.Right bank front 02 sensor. When an HO2S sensor indicates lean at the end of a test, the system is trying to correct for an over-lean condition. The code is set when the fuel control system no longer detects switching for a calibrated amount of time.In other words the 02 sensor is indicating lean and the fuel trim has reached the programed limit trying to correct it.
There are many things that could cause this like a bad 02 sensor,a vacuum leak,a leaking or contaminated fuel injector/s,a stuck open PCV valve,leak in hose between MAF sensor and engine causing un-metered or unmeasured air entering the engine,exhaust leak,improperly seated oil dipstick,stuck EGR valve.
Check PCV valve first if it is stuck open if you pull the hose off of the valve cover that hooks to the air tube between MAF and engine you will feel a strong vacuum pull there,normal you would hardly feel it.
Posted on Mar 11, 2009
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