Engine control light and too high consumption

[Dani1]

Hello Pathfinder Community

 

I recently bought a 2002 Nissan Pathfinder with the 3.5l V6 Engine and restored it a little bit (welded Rust, replaced some Parts,...). I dont know, what the exact name of my model is, because here they are named differently to the US.

 

Now I have two problems that might be related.

 

The first problem is that after about three days the engine warning light came on. A read-out device from a colleague brings up the errors P0158 and P0138. So O2 sensor bank 2 sensor 2 and O2 sensor bank 1 sensor 2.

What could be the problem? I don't think it's the sensors. It would be a bit unlikely that both of them would break down at the same time. By the way, the engine runs cleanly and I can't detect any jerking or similar.

 

My second problem is the fuel consumption. Of course I know that it is not an economical car. I reckoned with 13-15l/100km (18.1-15.7 mpg) with a decent driving style.

I mainly drive in the 50s (31mph) and 80s (50mph), often with cruise control and not at all with a heavy foot on the accelerator. A mountain pass can also be part of the trip. But it's a small percentage.

Tyres can also have a big influence. I put on new Yohohama Geolandar A/T G015 tyres and drove with 2.5 bar (36psi). Now I have pumped up to 3.2 bar (46psi) because of the consumption. I want to see if I notice a difference.

I now drive with a consumption of about 17.5l/100km (13.4mpg).

 

Can these problems be related?

 

If you need anything else to know, just ask me. And sorry if my english isn`t perfect

 

Thank you for your answers.

 

[hawairish]

Just to be sure, you're throwing both codes separately?  Reason for asking is because the Factory Service Manual describes them together; P0138 for RH side and P01538 for LH side.  Switzerland is LHD drive?

 

If you are getting both codes, the FSM does indicate that there's a common 15A fuse, #25 (fuse box under steering column, 2nd column, 6th row).  From the fuse box, it's a red/yellow wire that leads to a brown 24-pin harness behind the center dash, where it becomes a red/white wire at pin #3 of the o2 sensor harnesses in the engine bay.  Those harnesses will be dark blue 4-pin; RH side at near cylinder 5 and LH side closest to cylinder 1 (closer to the oil cap).  You should be able to probe those for 12V I'd think.

 

Service manuals available here: https://www.nicoclub.com/nissan-service-manuals

 

Drill down to your truck and year, then check out the Engine Control System chapter.  A layout of all harness locations can be found towards the end of the Electrical System chapter.

[Slartibartfast]

 

The codes appearing together, so soon after you bought the truck, makes me suspect that the previous owner had the same issue, cleared the codes, and sold it to you before the computer noticed that the problem was still there. The service manual Hawairish linked to will be your friend in tracking this down. Hopefully it's a wiring or sensor issue and not the catalytic converters. And hopefully tracking this down fixes your fuel consumption! 

 

While you're bringing the truck up to speed, look into checking the power valve screws. Common issue on the early VQ. Hopefully unrelated to this issue.

[Dani1]

On 1/4/2023 at 12:57 AM, hawairish said:

Just to be sure, you're throwing both codes separately?  Reason for asking is because the Factory Service Manual describes them together; P0138 for RH side and P01538 for LH side.  Switzerland is LHD drive?

 

If you are getting both codes, the FSM does indicate that there's a common 15A fuse, #25 (fuse box under steering column, 2nd column, 6th row).  From the fuse box, it's a red/yellow wire that leads to a brown 24-pin harness behind the center dash, where it becomes a red/white wire at pin #3 of the o2 sensor harnesses in the engine bay.  Those harnesses will be dark blue 4-pin; RH side at near cylinder 5 and LH side closest to cylinder 1 (closer to the oil cap).  You should be able to probe those for 12V I'd think.

 

Service manuals available here: https://www.nicoclub.com/nissan-service-manuals

 

Drill down to your truck and year, then check out the Engine Control System chapter.  A layout of all harness locations can be found towards the end of the Electrical System chapter.

Thanks for your reply and sorry for getting back to you so late.

 

Yes Switzerland is LHD.
Yes, both codes are displayed in the app (picture attached).

I will check the voltage soon when I find what you described.

[Dani1]

On 1/5/2023 at 10:46 AM, Slartibartfast said:

 

The codes appearing together, so soon after you bought the truck, makes me suspect that the previous owner had the same issue, cleared the codes, and sold it to you before the computer noticed that the problem was still there. The service manual Hawairish linked to will be your friend in tracking this down. Hopefully it's a wiring or sensor issue and not the catalytic converters. And hopefully tracking this down fixes your fuel consumption! 

 

While you're bringing the truck up to speed, look into checking the power valve screws. Common issue on the early VQ. Hopefully unrelated to this issue.

Thanks for your reply.

 

Yes i really hope, that its an electrical problem.

But I don't think the catalytic converters are defective. Because wouldn't it be strange if both were broken at exactly the same time?
and I was at the MFK (Motorfahrzeugkontrolle = motor vehicle inspection) a fortnight ago. We need that here every two years to be allowed to drive the car. They check the pollutants in the exhaust. If the catalytic converters were defective, it would have been noticed?

 

And thank you for the advice with the power valves screws. I will check that soon.

 

[Dani1]

By the way, the error deleted itself two days ago. I'm curious to see if and when it comes back...

Or does that mean something when the error clears itself?

[Slartibartfast]

That's odd. I think some codes self-clear if the computer goes a certain number of drive cycles without seeing the problem again. Hopefully a fluke--if not, chase it when it returns. 

 

And yes, I would assume passing the smog test means the cats are working.