Is it common for O2 sensors to fail in these trucks? I took the truck at work to get inspected, and it failed because there were codes in the computer. Both banks showed lean, and there was the 1443 that seems to be a common problem with the rangers too. Would both O2 sensors fail at the same time? Is the easiest fix for the purge system just to replace the parts, or try and clean them out? The truck seems to not want to go from a dead start, but once it gets going, it drives fine. I have noticed spark knock when a load is on the engine in overdrive only. It's got a 3.0 and a 4 speed auto. Thanks for your help.

 

I got the part about the Ranger showing a P1443 EVAP Control System Canister Purge Valve code. The code is set when a leak or blockage between the intake manifold, the EVAP canister purge valve and the EVAP canister is detected by the PCM.

Possible P1443 Causes:

- Pinched, blocked or plugged fuel vapor tubes/hoses (except between fuel tank and EVAP canister)

- Damaged EVAP canister

- Disconnected, cracked or cut fuel vapor tubes/hoses (except between fuel tank and EVAP canister)

- Damaged EVAP canister purge valve

Tip: Check for audible vacuum noise in the engine compartment or significant fuel odor in the engine compartment or near the EVAP canister.

Regarding the banks showing lean, I will assume that the codes set were P1071 and/or P1074. Here are things to check regarding lean bank codes:

Fuel system
- Excessive fuel pressure.
- Leaking/contaminated fuel injectors.
- Leaking fuel pressure regulator.
- Low fuel pressure or running out of fuel.
- Vapor recovery system.

Induction system:
- Air leaks after the MAF.
- Vacuum Leaks.
- PCV system.
- Improperly seated engine oil dipstick.

EGR system:
- Leaking gasket.
- Stuck EGR valve.
- Leaking diaphragm or EVR.

Base Engine:
- Oil overfill.
- Cam timing.
- Cylinder compression.
- Exhaust leaks before or near the HO2Ss.

This information is from the "OBDII Codes" section of the thread entitled "Sticky: Technical Information" which is locked at the the top of this Forum.

 

Thanks for all of that, I guess I should have looked at some of those things more closely. The guy who was doing the inspection said that I should just replace the O2 sensors, but I don't like to just throw parts at it without diagnosing the problem. Since it's a company truck, they will probably take it to a shop, but this way I know what to get the shop to look for and test. Thanks again.

 

I have a 97 4.0 that was giving a 171/174 code..too leanfrom both banks...after replacing 3 o2 sensors,maf ...turned out to be the rubber o-ring seals under the air intake housing,$6.00..Hope this helps good luck mike

 

I would have to agree with a vacuum leak or even an exhaust leak throwing both banks as lean.

 

Let us know how it turns out

 

I'll keep you guys posted... thanks for all your help

 

i think they had troubles with injector o-rings in 97-98 also.there may be a tsb on it.good luck

 

Just read on where somebody with a '96 4.0L (123K) had both codes P0171 and P0174 coming back, ended up being a rubber O-Ring on the EGR tube. Also in the same thread, another guy said he had a leaky intake gasket that caused the codes.

I think what is becoming clear is that a lot of things should be checked before going ahead and replacing both of the O2 sensors.