Check engine light came on about a week ago. Read the codes and I got:

O2 Sensor Heater Circuit Bank 1 Sensor 2

O2 Sensor Circuit High Voltage Bank 1 Sensor 2

Cylinder 5 Misfire Detected

I disconnected the negative battery terminal to clear the codes, which it did, but after a short drive the CEL came back on. Not flashing, just came on.

The plugs, wires, cap and rotor are all about a year old (less than 3000 miles on them, truck only has a little over 62K miles). I pulled all the spark plugs since I was already in there and they all looked fine. I put anti seize on them and di electric grease on the boots since that wasn't done when they were installed. Took it for a 10-15 minute drive. It was fine until I put my foot into it (over 3K rpm). The CEL flashed about 10 times then stayed on again. I did the "turn the key ON and OFF three times" trick to see the codes again... just a cylinder 5 misfire this time. No O2 sensor codes.

In searching the forum I found the TSB dealing with plug wire routing, so I'll try that next. After that I'll try switching the injector with another cylinder I suppose.

I've never pulled the fuel rail/injectors before. Do I have to disconnect the fuel line that goes into the fuel rail in order to swap the #5 injector with another cylinder? Or will I have enough clearance without removing the fuel line? If I'm not mistaken I think removing that fuel line requires a special tool.

Also, what is with the flashing CEL? Does that mean the cylinder is misfiring at that moment? And it stops misfiring when the CEL stops flashing and remains solid? Or does a solid CEL indicate a continuous misfire? Would the CEL shut off if it stopped misfiring? Or would I have to clear the code for the CEL to shut off?

Sucks that this truck is my daily driver. I don't like the idea of driving with a misfire. Any help is appreciated.

 

Flashing CEL indicates cylinder misfire. The lite stayed on because it set a code. (cylinder 5 misfire.)

Bank 1 Sensor 2 is the post-cat O2 sensor. Sounds like it is having heater issues. Probably wouldn't hurt to just replace it.

Should be able to swap injectors (do 5 and 7, see if the misfire moves with the injector) without disconnecting fuel line. Although, you can pick up the tool at most any auto parts store pretty cheap.

 

Thanks. I just wanted to make sure the cylinder was firing and it wasn't a CONSTANT misfire. I wouldn't really want to drive it if it was consistently misfiring. I'll work on it when I get time and report back the solution. I have a feeling it might be the plug routing.

 

Anti seize can cause plugs to misfire and is not recommended by them that the make spark plugs. Plug wire routing probably wouldn't give you consistent hard code on a single cylinder, unless it's just a bad wire on 5. You could also check compression. Or even could switch that plug. Hold the anti sieze, it can mess with the spark path.

 

Well I suppose it was the plug routing it a way. I pulled the #5 wire today and wouldn't you know it - melted in one spot. It must have been laying on the exhaust header.

Another question, what's the deal with that gasket that sits between the air cleaner and the throttle body? Would removing it cause a vacuum leak? The damn thing sits so loose on there it makes putting the air hat back on a real pain. I suppose I should just replace it.

 

Might get a whistle without it. Mine has been gone for quite some time. I just don't worry about it.

 

My discovery of the burnt wire was at work last night. I zip tied it up off of the exhaust header thinking it would help. Not so - the truck misfired all the way home, about a 5 mile drive. Got new plug wires today (autolites) and since it's in the single digits here I thought I'd half *** it by just replacing plug wire #5 for now. I guess that was a bad idea because now I'm getting a p0300 code with p0301 and p0303.

 

Or misfiring for 5 miles screwed the cat.

 

Could be the anti seize, depending how much you used. Spark can arc down the outside of the shell to the electrode.

 

I don't think it was the anti seize. Directly after putting it on the threads the truck ran the same as it did before. Intermittent cylinder 5 misfire. It didn't start getting really bad until I messed with the burnt plug wire.