Hi everyone.

I just joined this forum in hopes you guys can point me in the right direction with the codes that I am seeing. First, let me give a little back story...

This past August, my son, on his 17 birthday weekend, fell asleep behind the wheel of my 99 Mazda B2500 (4 cycl/4x2/reg cab) and rolled it twice! He walked away with minor scratches (thank God). However, the B2500 was totaled. So I wanted another small truck and, since I am kinda brand loyal to Mazda (Mazdaspeed3, Mazda3, Mazda2, CX-5), I found a used 2002 Mazda B4000 Ext. Cab 4X4 4.0L w/ 118K for $4995.00. The maintenance records showed that the vehicle had been maintained by a local Mazda dealership (PA), accomplishing all the major checks (40k, 60k and 80k). So I felt very comfortable buying the truck but soon after I purchased the truck, I got the "check engine" light.

So off to AutoZone I went and they pulled the codes as P0171/P0174 "bank 1 and 2 lean". Their system said to replace the PVC Valve, and for $5.99, I bought one and replaced it. Two days later, the light returned and I went back to AutoZone. Again, the same two codes and recommendation to replace the PVC Valve. Knowing that wasn't it, I left and started my internet search. I read what these codes meant and possible solutions to correct them. First, I purchased a scanner from Harbor Freight ($89) and then a new MAF sensor with housing ($35) from Amazon. Before installing the MAF, I plugged in the scanner and got: P0171, P0174 and the OSBD II showed red for FUEL, CAT, HTR, O2, EGR, EVA and AIR (I think that was it). Once I replaced the MAF, the AIR and HTR indicators went green. I then replaced the EGR Valve ($52) and then the O2 and FUEL indicators turned green. I read that the feedback senor to the EGR could throw the P0171/P0174 codes too, so I replace it next ($35). Oddly enough, the CAT indicator turned green. I still have the EVA indicator as red and the P0171/P0174 codes.

Next, I sprayed brake cleaner around the intake manifold, looking for a leak there. No change in engine rpms. I sprayed the vacuum lines. No change in engine rpms, either. So now you guys are caught up to where I am at now (scratching my head). The truck drives fine. It does not run rough at idle or while driving. It seems to have plenty of power. Oddly, it seems to be getting better mileage then my B2500. I am averaging 290 miles on a single tank of gas (mostly highway). Not sure if that's good, bad or ugly?

What do you think I should look for/do next? I don't know much about fuel trims so I will post pictures of the scanner monitor soon. Maybe, that will shed some light on my situation...

Thank you

 

Ok, its been several weeks and I think I found the issue. The next evening, after the above posting, I saw a youtube video that basically pointed to the PVC line itself as being the problem. Apparently, the rubber elbow attaching to the throttle body often cracks. I guess with it being covered by the upper coolant line, I didn't see it nor did the brake cleaner. Anyways, a 10 dollar PVC elbow from Autozone later and the P0171/P0174 codes are finally gone. I will attach pictures.

 

Good, you found the cause. If Dorman makes a replacement part, then we know that this is a common part to go bad. and remeber that your Mazda is actually a Ford Ranger, so there's help there too; B4000 is bigger engine that what he had before; get him involved in the repairs !!

On my 1998 Frontier, I had an EGR code a decade ago due to a similar crack in the 2-inch hose under the EGR valve.

And I have a Dorman electric in-dash actuator in our 2005 Yukon to direct the AC air.