What are the symptoms of a bad 02 Sensor? I have a 1999 F-150 5.4. Over the last few months, I feel that my truck is losing some of it's horse power. When starting the truck, it doesn't start up with the normal feeling that it once had. The check engine light came on yesterday and Autozone said that it was the o2 sensor on the left side. He did not give me the code, just that it was the left side. How many sensors are there? I know of at least two. Any info is appreciated.

 

There are four O2 sensors on your truck.

There's two before the cats, and two after the cats. The two after the cats simply tell the computer if the cats are working correctly or not. The two before the cats are the ones probably causing your problem. If AutoZone is to be trusted replace your front left O2 sensor. Let us know what happens. Good luck.

*edit*

Be sure to reset your computer by disconnecting the the battery for 1/2 an hour or so. You _WILL_ lose all your radio presets. But the computer needs to be reset so it will realize it's getting correct info from the replacement O2 sensor.

 

What was the code. They seldom fail. I would start by checking the PCV hose elbows. Especially the one where it attatches to the rear of the intake. I would also clean the MAF.

 

The guy that took the codes didn't give them to me. He just said left side. I asked him for them and he said what does it matter! I asked him how much the sensors were and he said that they start at $46. I said thanks and let him know that I would be going to O'reilly Auto Parts.

 

I simply hate bad customer service reps. I ALWAYS tell a manager if somebody has their head up their butts. If they are the manager, I will call the district rep. Don't stand for that crap and make a call.

 

My local AutoZones are quite helpful. Sorry you got ahold of an unhelpful idiot.