Codes PO181 and PO171

FRONTIER2017

MEMBER
2017 NISSAN FRONTIER
90,000 MILES

I drive the vehicle listed above S, four cylinder automatic with 90,000 miles on. I was having drivability issues and it would shut off sometimes and was running really rough after I cranked it back up. My code scanner pulled po181 and po171. One code was for the temperature sensor and the other one was a lean condition which I assumed was related to the fuel temperature sensor not giving the PCM correct data. I replaced the fuel pump and fuel sending unit with fuel temperature sensor attached and now I have no fuel pressure at all. I ordered an intelligent power distribution module which has the fuel pump relay in it new from Nissan. I am still not getting any fuel pressure and checked the connections at the fuel pump and all is good. My question is what do I check next? Is there a sensor on the engine somewhere that's telling the PCM not to send power to the fuel pump?

7 Replies

KASEKENNY

MECHANIC
18,907 POSTS

We need to start with checking to see if we have power at the pump. If you have power there then you have a faulty pump.

https://www.2carpros.com/articles/how-to-check-wiring

If you do not have voltage there then we need to go to the relay and test to see if the relay is the issue or the PCM is not grounding the relay.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

If you look at the wiring diagram you should have power coming from fuse 48 with the key in the on position. If you do then you will not have any voltage coming out on the red wire until the PCM grounds the relay.

On the other side of the relay the ignition switch provides the 12 volts that will energize the relay but it is low side driver. This means the control component (the PCM in this case) is on the ground side of the component which is the relay in this case.

So when the PCM wants the fuel pump on it grounds this circuit on the Purple wire and the power flows through the relay and it pulls the relay switch closed which then allows the power from fuse 48 to turn the pump on.

We need to test the fact that the PCM is grounding the relay by connecting your red meter lead to battery positive and then put the black lead on the relay terminal of the purple wire. Then turn the key on. The relay should be out at this point. If your meter reads 12 volts then the PCM is operating properly.

Let me know if you have questions on this and then what you find.

Images (Click to make bigger)

SPONSORED LINKS

Was this

answer

helpful?

Yes

Friday, May 21st, 2021 AT 2:57 PM

MIKECAMP71

MEMBER
3 POSTS

Thanks for the information I really needed those wiring diagrams to help me out. I have been reaching out for a week trying to find information on this truck and you are the first to reply really greatly appreciate your help.

Was this

answer

helpful?

Yes

Friday, May 21st, 2021 AT 6:14 PM

KASEKENNY

MECHANIC
18,907 POSTS

Glad we could help. Feel free to check in with us first next time because we have AllData and Mitchell which has the entire service manual for your vehicle.

Let us know if you have other questions. If they are not related to this issue, feel free to get a new post started and we will get on that as well. Thanks

Was this

answer

helpful?

Yes

Saturday, May 22nd, 2021 AT 8:03 AM

MIKECAMP71

MEMBER
3 POSTS

Yes, thanks a lot for everything. Come to find out on this issue was the new aftermarket fuel pump. I am getting 12 volts positive and a ground to the new fuel pump that it does not work. I believe the issue is the ground wire on the new fuel pump is loose and not making a good connection on the inside of the fuel tank. My plan is to get in touch with Napa and exchange the fuel pump and try again.

Was this

answer

helpful?

Yes

Saturday, May 22nd, 2021 AT 8:20 AM

KASEKENNY

MECHANIC
18,907 POSTS

Great info. Thank you so much for that info. Please let us know if you get it changed out (again) that it solves the issue. It would be a good confirmation for others that visit this page that we can't always trust new parts.