Anyone else getting P0171 and P0174 on a 2019 Tundra?

Toyota Truck, SUV and Vans Forum Toyota Tundra
1

So I’m dealing with these error codes P0171 and P0174 on my 2019 Toyota Tundra, and my check engine light is on. There’s a hesitation during takeoff too. It’s been like this for a while. Anyone have advice on what else I should try?

2

Those codes usually mean it’s running lean. Have you checked for any air leaks or fuel pressure issues?

3

Taj said:
Those codes usually mean it’s running lean. Have you checked for any air leaks or fuel pressure issues?

Yeah, I’ve replaced the intake spark plugs, upstream sensors, and air filter. I also swapped the MAF sensor about a year ago, but no luck finding any vacuum leaks.

4

@Ashby
If there’s no leaks, maybe try checking the fuel trim? It might tell you if it’s actually running lean.

5

Did you check the PCV valve and hose connections? Those can sometimes cause lean conditions if they’re not sealed right.

6

Bradley said:
Did you check the PCV valve and hose connections? Those can sometimes cause lean conditions if they’re not sealed right.

Not yet, that’s a good point. I’ll look into it and see if there’s anything loose.

7

Did you check the fuel trim readings? I know it helps to use live data if you have access to it.

8

Finnley said:
Did you check the fuel trim readings? I know it helps to use live data if you have access to it.

I don’t have live data on my setup, unfortunately. I do have some freeze frame data, though.

9

@Ashby
Gotcha. What’s the fuel trim like in your freeze frame?

10

Finnley said:
@Ashby
Gotcha. What’s the fuel trim like in your freeze frame?

Longft1 is at 23.4% and Longft2 is at 33.6%. Not sure what else I can do with that info.

11

If you’re still seeing lean codes, maybe check the injectors or fuel pump. Low fuel pressure can mess with the air-fuel ratio.

12

TacomaTribe2 said:
If you’re still seeing lean codes, maybe check the injectors or fuel pump. Low fuel pressure can mess with the air-fuel ratio.

Yeah, I might have to go that route. Not looking forward to taking the fuel tank off, though.

13

@Ashby
Totally get that, but it might give you some answers. If the pressure’s low, it’s probably time to look at the pump.

14

Could different O2 sensors make a difference? Like if they’re not an exact match?

15

Dara said:
Could different O2 sensors make a difference? Like if they’re not an exact match?

Funny you mention that! I replaced them with Denso sensors. It worked fine for a few days, but then the codes came back once the engine warmed up.

16

@Ashby
That’s odd… did you replace both at the same time? Maybe one was just a bit off?

17

Dara said:
@Ashby
That’s odd… did you replace both at the same time? Maybe one was just a bit off?

Yeah, both were swapped at the same time. Guess it’s unlikely both new ones would have the same issue.

18

Did you ever run a smoke test? Sometimes leaks are hard to spot without one.

19

Wren said:
Did you ever run a smoke test? Sometimes leaks are hard to spot without one.

I did a smoke test, but didn’t find any leaks. Might be time to check out the injectors or fuel pump.

20

Any chance it could be the intake manifold? If there’s a crack or something, that could explain the lean codes.