CEL

[Chicano2005]

im just wondering if anyone else had this same issue with their truck.

if so, can someone give me some advise.

 

the guy at autozone said to use injector cleaner(lucas)

fill the whole tank and drop in two lucas bottles.

wait and see if the light stays on for a week to go get it checked at a mechanic.

 

i was on the highway and the light came on.

had it checked at autozone and it got two codes.

 

1) P0300: random cylinder misfire detected.

probable cause

1)ignition system fault.

2)fuel system fault.

3)large vacuum leak.

4)MAF sensor fault.

5)AF/H02S (air-fuel/heated oxygen sensor)

 

2) P0138: heated oxygen sensor - bank 1 sensor 2 (H02S12) circuit high voltage.

probable cause

1)open or short circuit condition.

2)high fuel pressure or leaking injector.

3)faulty heated oxygen sensor - bank 1 sensor 2 (H02S12)

 

 

thanks for reading! i hope some can help me!

[vanuatoo]

If you have high mileage car, it's probably O2 Sensor P0138, that causes code P0300 to come.

I would first change O2 sensor and see what'd happen.

[Chicano2005]

If you have high mileage car, it's probably O2 Sensor P0138, that causes code P0300 to come.

I would first change O2 sensor and see what'd happen.

 

thanks for the reply!

it reads 125,xxx!

i was thinking the same thing.

im also thinking of doing the complete tune up!

[Precise1]

I recently fixed a P0301 and P0138 code. My issue was that the injector for cylinder #1 was intermittently failing when hot and the Bank 1 #2 O2 sensor was getting high readings. (I was told that the #2 O2 sensors do not affect the air/fuel mixtures but are more of a secondary verification)

 

I replaced the injector and the O2 code quickly cleared its self and the CEL went out before I ordered and replaced the O2 sensor.

You can read up on it here if you wish... http://www.nissanpathfinders.net/forum/index.php?showtopic=27522

 

Since you have a random misfire (not a specific cylinder) I'm guessing more ignition related components like cap/rotor and perhaps wires. At least inspect these.

The one bank fouling, not both makes me wonder if it is a cylinder specific problem like a wire or plug??

 

If you do have injector issues, I have 5 spare injectors and new seal kits that may be of use to you.

 

B

[Chicano2005]

well i just found this code chart!

 

http://forums.nicoclub.com/obd-ii-code-chart-t244617.html

 

According to the chart code P0138: O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)

and code P0300: Random/Multiple Cylinder Misfire Detected.

 

Im not really good at car mechanics.

what does P0138 refers to, is it the o2 sensor itself? or a just a sensor?

and on P0300 what cylinder does it refer to? like a brake master cylinder?

 

sorry i only have basic knowledge!

 

 

EDIT: and if i replace lets say bankd 1 sensor 2 will that clear that code?

or is it something else that causing the problem?

Edited November 8, 2010 by Chicano2005

[Chicano2005]

ok so i did a little research and here's what i have found so far.

 

From the FSM, P0300 causes include:

 

- Improper spark plug

- Insufficient compression

- Incorrect fuel pressure

- The injector circuit is open or shorted

- Injectors

- Intake air leak

- The ignition secondary circuit is open or shorted

- Lack of fuel

- Drive plate or flywheel

- Heated oxygen sensor 1 (front)

 

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A P0300 diagnostic code indicates a random or multiple misfire. If the last digit is a number other than zero, it corresponds to the cylinder number that is misfiring. A P0302 code, for example, would tell you cylinder number two is misfiring. Unfortunately, a P0300 doesn't tell you specifically which cylinder(s) is/are mis-firing, nor why.

 

A code P0300 may mean that one or more of the following has happened:

 

* Faulty spark plugs or wires

* Faulty coil (pack)

* Faulty oxygen sensor(s)

* Faulty fuel injector(s)

* Burned exhaust valve

* Faulty catalytic converter(s)

* Stuck/blocked EGR valve / passages

* Faulty camshaft position sensor

* Defective computer

 

Possible Solutions

 

If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.

 

If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.

 

Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.

 

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Nissan Technical Service Bulletin #NTB02-006 addresses the following codes for 2001 Pathfinders:

 

^ P0138

^ P0139

^ P0140

^ P0158

^ P0159

^ P0160

 

The bulletin states that if you have any of the codes, replace the incident O2 sensor. If you have codes P0138, P0139 or P0140, replace the rear RH O2 sensor with the following part, based on pro date:

 

Built up to 8/1/00: P/N: 226A0-4W001

Built on 8/2/00 or later: P/N: 226A0-4W010

 

The TSB also has you check the ECM part number and compare to a list of ECM part numbers on the bulletin, which will require the use of a CONSULT II scantool (meaning a trip to your Nissan dealer. Depending on the ECM program currently installed in your vehicle, it may need to be updated to the latest program revision.

 

Rear O2 sensors are for testing catalytic converter efficiency and have no affect on drivability, unlike the front O2 sensors, which the ECM uses to help provide the proper air/fuel ratio.

 

As far as O2 sensor identification, "Bank 1" is the engine bank that starts with #1 cylinder. "Sensor 1" is the front or "upstream" sensor. "Sensor 2" is the rear or "downstream" sensor. Bank 1 on the VQ engine is the right side bank and Bank 2 is the left side bank.

 

 

 

hopefully some can help me understand this a little bit more. any help is greatly appreciated.

[Precise1]

what does P0138 refers to, is it the o2 sensor itself? or a just a sensor?

and on P0300 what cylinder does it refer to? like a brake master cylinder?

Yes, they are talking about the O2 sensor.

The cylinder is what the piston rides in, with a fuel injector, spark plugs and valves above it. You know, the bang chamber...

 

and if i replace lets say bankd 1 sensor 2 will that clear that code?

or is it something else that causing the problem?

Maybe and possibly. Don't worry about that right now, as I said above. Fix the misfire first...

 

Here is probably the best place to start and what to look for/replace, quoted out of the above text.

im also thinking of doing the complete tune up!

Since you have a random misfire (not a specific cylinder) I'm guessing more ignition related components like cap/rotor and perhaps wires. At least inspect these.

The one bank fouling, not both makes me wonder if it is a cylinder specific problem like a wire or plug??

* Faulty spark plugs or wires

* Faulty coil (pack)

* Faulty oxygen sensor(s)

* Faulty fuel injector(s)

* Stuck/blocked EGR valve / passages

 

Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.

You need to go through and inspect/test/replace the items on this list first, odds are your problem is one of them...

 

B

[Chicano2005]

thanks a lot!

 

i will do the basic tune up first since winter is around the corner.

then i will ask my uncle to check the injectors etc.

money is a little tight right now!

 

thanks again!

Edited November 10, 2010 by Chicano2005