96' windstar P0151,P1151 and P0304

Hello all,
I am new to this forum but have found it very interesting and helpful. So I thought I would post and see if anyone could help me out. I have a 1996 Ford Windstar 3.8L engine with the check engine light on at start up and then while driving it will begain to blink and engine will miss. So I had it tested with a scanner and codes that came up were.
P0151-Lack of H02521 switch-sensor Indicate Lean.
P1151- Heated o2 sensor circit low voltage (Bank 2 sensor 1)
P0304- #4 misfire
So I changed plugs and plug wires. Changed PVC valve and checked for any vacume leaks. My first question is Where is Bank 2 sensor 1 located? So I can change correct o2 sensor.
Has anybody had same trouble or can someone suggest what I should do next.

Thank you,
Joe

From what I can remember I belive that is the firewall side upstream O2 Sensor.

From what I can remember I belive that is the firewall side upstream O2 Sensor.

Hi
I believe you will find it the other way around. Cylinders 1,2,3 (bank 1) are across the firewall, cylinders 4,5,6 (bank 2) are across the front. So bank 2 upstream should be the "easy" one in the front of the engine compartment. Here is a link:

http://www.autozone.com/servlet/UiBroker?UseCase=C001&UserAction=performSearch&Parameters=Auto+Store%7C%7ESPECIFICATIONS%7C%7EFIR ING+ORDER

Hope that helps.

Easy way to remember.... Bank 1 is the bank with cylinder #1.
Cylinder #1 is on the back (firewall side) of the engine....on the passenger side.
That would make the front bank of cylinders #4, 5, 6 to be Bank #2.
Upstream is before the catalytic converter.

That said, if you are changing one oxygen sensor, I would replace both upstream sensors, so that you have a matched pair.
I would buy the Motorcraft brand, which you can get a www.rockauto.com for a decent price.

Also, I would take a good look at the sensor that you are replacing....look for any signs of coolant (green stain) on the sensor.
Coolant can take the sensor(s) out.
The most likely cause for coolant leakage to get into the cylinder(s) and onto the oxygen sensors is the lower intake manifold gasket.
The head gaskets are not as high a failure item on the post '95.

Also, take a very good look at the wiring for the sensors to make sure that they are not against the exhaust system. That is more often a problem with the other oxygen sensors, that are further back, but worth checking out.

Bank 1 (cyl 1-2-3) firewall side. Bank 2 (cyl 4-5-6) Radiator side. Yeah well. My guess is . . . ignition. I'll bet a (going) bad coil pack is causing all these codes. Check it first. If it checks out OK when the car is cold, check it again when the symptoms appear.

Karl