2001 Nissan Pathfinder with codes: P1320, P0138, P0304

[nissan2986]

I am trying to help someone with a Pathfinder that is throwing a few codes. I told them to go to autozone to pull the codes for free, and I will try looking on the internet for a solution and parts. I was expecting they have 1 code, but they gave me 3. I don't want to buy them unnecessary parts if one faulty part is causing all 3 codes.

A bit of history and symptoms. A while back the car had a check engine light that came off and on. When autozone first pulled the code, it said something that translated to a faulty part in the fuel tank (Fuel Tank Pressure Sensor?) However, I don't see anything related to that anymore, yet the part was never replace. The car seems rough during cold starts. Once it is hot and on the highway it feels like nothing is wrong.

Here is what autozone said:

"P1320 ignitaion circuit
open or short circuit cond.
failed power transistor unit
failed ignition ballast resistor cam position system failure
P0138 heated oxygen sensor
open or short circuit condition
high fuel pressure or leaking injector
faulty heated oxygen sensor-bank 1 sensor 2
P0304 4 cylinder misfire detected
ignition system fault, fuel system fault
vacuum leak affecting one cylinder
engine mechanical condition"

The owner of this car had a coil replaced some time ago. I am assuming #4 needs replacing now.

What oxygen sensor is "bank 1 sensor 2"? Would that be "upstream left" or "upstream right" or after the cat? The parts website lists them as "upstream, downstream, right or left". It also says "to or from 8/00" Does that mean before or after a build date of Aug 2000?

cam position system failure? camshaft position sensor?

Could "high fuel pressure or leaking injector" be caused by the "Fuel Tank Pressure Sensor"?

Finally, a vacuum leak?!? Could it be "Fuel Tank Pressure Sensor"? The car only has 80,000 miles and sounds like it has all sorts of problems. The owner is not good with cars so I am trying to help them out as they don't have much money to send it to a dealer.

[Towncivilian]

Make sure ignition coil #4 is completely plugged in. If that doesn't solve anything, try swapping it out with an adjacent ignition coil and see if the problem moves. In order to get to ignition coil #4, you will have to unscrew the IACV which is in the way. You can find a guide here.

I think this would be the oxygen sensor you require.

Rough idling may be caused by misfiring (which is probably due to bad ignition coil), or a dirty MAF sensor. The guide I linked to above also has a brief guide on cleaning the MAF sensor, but you should probably try fixing the codes first.

I would assume it's a 2001 year PF (manufacturing dates 01/01/2000-08/31/2000 are 2001 and 09/01/2000-06/30/2001 are 2001.5). With the 2001.5 model, ignition coils were changed.

[nissan2986]

For any of this work (the O2 sensor, etc), does anything need to reprogrammed by the dealer? I heard the ECU needs to be cleared by the dealer or is this something I can do by unplugging the battery?

[Towncivilian]

For any of this work (the O2 sensor, etc), does anything need to reprogrammed by the dealer? I heard the ECU needs to be cleared by the dealer or is this something I can do by unplugging the battery?

Not to my knowledge. All you should need to do is clear the codes by disconnecting the negative battery terminal for several hours (which you should already be doing before attempting any of this, anyway) or by using a code scanner tool.

[ARKQX33V6]

Since money is tight, and what else is knew?
Let's start with #4 plug and work backwards. Plug, wire, coil, interconnects, transistor. Likely not transistor, but check plug and HT lead, then the distributor. Inside look for dirt, dust and clean, clean underside of cap. Stop

Faulty part in fuel tank could cause rough idle if gas is not getting through, so verify pump, fuel filter and fuel rail. Stop

At 80K miles the O2 sensors are slow acting, the rich to lean mixture may be all over the place (miss fire?) Pull all plugs investigate, cleanliness colour tan amount of crud let us know. Stop

The front 2 O2 sensors are probably slow causing the back 2 to eventually report catalytic problems, but the front must be good before playing with the exhaust downstream of the front sensors. At 80,000 m has the vehicle had O2 changes? Stop

High fuel pressure is rare, the regulator should be tested but test the fuel rail no guessing allowed. Guess what is wrong and you will be in the poor house, know what is wrong by investigating, testing, so that means money has to be spent renting or buying test equipment or using what you have to find the answer. Don't guess!

Vacuum leak at what location working what system?

Any leaks to the tank should be caught by the evap sensors
Vacuum leaks at the motor can be tested with a source of Hydro carbon that will speed up the engine, propane for example.

The stop in this write up is a section for you to perform the tests.

Vacuum is created when the pistons are drawn down, a vacuum container in line is to help maintain vacuum because vacuum in an engine is up and down as the pistons at differing times draw .

Fuel pressure at 40 PSIG on the rail feed and a bit less on the rail load must maintain a minimum pressure to the fuel injectors.

The fuel injectors will oscillate and the spray pattern should be tested and the spray pattern changes as to motor conditions via the ECU.

Sensors like O2 are very sensitive to voltage and the voltage changes around the threshold voltage.

I understand saving money, but there are times because of technology that you could make the condition worse.

The work outlined requires testing equipment and anyone willing to work on their vehicle should have a minimum set: As far as testing goes:
Spark tester
Vacuum gauges, gas pressure gauges
Timing light
Multi meter
Wire markers
Compression tester
Remote starter switch
Feeler gauges flat and wire
Tire pressure gauge
Battery hydrometer
Anti freeze hydrometer
Battery charger able to charge at 3 rates, trickle, 10A and 50 A for equilization

Doing the work is satisfying when done and done right, but it will cost you the tools, hand tools sometime the specific tool and testers and the longer that the keep a vehicle the more into it you will get. With time comes confidence and learning. Good luck

[Stephanie33]

did you ever resolve this? How? I have codes P0304 P1320 and P1145. It runs but barely, I swapped out all six coils and installed new plugs, new fuel filter, oil change. Swapped out crank and cam sensor and condenser.
any other ideas?