P0171

[sebastians]

So I just got a P0171 code, but I checked everything and there is nothing mechanically wrong, was thinking it was an issue with my bank 1 O2 sensor but am unsure, I had checked the fuel trims and it is saying its adding 32% extra fuel in that bank. I did have an exhaust leak on that side so maybe it finally died?

2003 Jeep Liberty Sport 3.7L 4x4 42RLE

 

[blackhawk]

I suggest you to disconnect the air hose that goes attached to throttle while you check the live data (long and short term) and if it varies on that bank, the sensor is running fine

 

[jbrigagao]

So I just got a P0171 code, but I checked everything and there is nothing mechanically wrong, was thinking it was an issue with my bank 1 O2 sensor but am unsure, I had checked the fuel trims and it is saying its adding 32% extra fuel in that bank. I did have an exhaust leak on that side so maybe it finally died?

2003 Jeep Liberty Sport 3.7L 4x4 42RLE

My Liberty 06 had this problem for no apparent reason. After several days of trying to fix it, I decided to change the battery and everything went back to normal. Interestingly, whenever I have to disconnect the battery for maintenance, this fault code reappears for a few days. Sorry for my bad English

 

[sebastians]

I suggest you to disconnect the air hose that goes attached to throttle while you check the live data (long and short term) and if it varies on that bank, the sensor is running fine

So I replaced both bank 1 sensors, the code is gone but after the engine hits operating temp it runs extremely rough, and i also get a heavy heavy fuel smell

 

[sebastians]

My Liberty 06 had this problem for no apparent reason. After several days of trying to fix it, I decided to change the battery and everything went back to normal. Interestingly, whenever I have to disconnect the battery for maintenance, this fault code reappears for a few days. Sorry for my bad English

That is interesting never heard of that before

 

[Ksat]

What brand O2 did you buy? NTK is the only brand you should be using. Many others are known to cause problems. Buy from a reputable source (a real auto part store, not ebay or Amazon).

 

[sebastians]

What brand O2 did you buy? NTK is the only brand you should be using. Many others are known to cause problems. Buy from a reputable source (a real auto part store, not ebay or Amazon).

I replaced both upstream and downstream with NTK's, got them special ordered from O'Rielly Auto Parts

 

[Ksat]

Interesting. Usually when there's problems going from open to closed (edited) loop it's the upstreams. Do you still have that exhaust leak you mentioned and, if so, is it before the upstream sensor? A leak before the sensor can cause that sensor mis-report.

 

[sebastians]

Interesting. Usually when there's problems going from closed to open loop it's the upstreams. Do you still have that exhaust leak you mentioned and, if so, is it before the upstream sensor? A leak before the sensor can cause that sensor mis-report.

Nope the leak is no longer present, and it was after both sensors

 

[Ksat]

You may want to disconnect the connectors on both upstream sensors then drive the car to see if things improve any once it warms up. It should force the PCM to stay in open loop mode. You can also pull a vacuum line and add propane or carb cleaner to the port to see if the fuel trim value changes on bank 1. Do this once with the sensors plugged in and you're in open loop.

Also, check the PIDs to see if anything looks eschew, such as IAT, MAP, coolant temp sensor, etc.

 

[sebastians]

You may want to disconnect the connectors on both upstream sensors then drive the car to see if things improve any once it warms up. It should force the PCM to stay in open loop mode. You can also pull a vacuum line and add propane or carb cleaner to the port to see if the fuel trim value changes on bank 1. Do this once with the sensors plugged in and you're in open loop.

Also, check the PIDs to see if anything looks eschew, such as IAT, MAP, coolant temp sensor, etc.

So I was driving my car with my scan tool plugged in and let the car fully warm up and then i went home and idled for a good amount of time, the fuel trims ended up going back to normal and fluctuating between +5-7 and then -3-4, not sure why it took this long but i think its good now

 

[KJowner]

That is interesting never heard of that before

This is a common Jeep issue, the cars use PCI bus, an older version of CANBUS. It runs at much higher voltage than CAN so low battery voltage on start up can cause all sorts of really strange problems.

 

[sebastians]

Ran a couple of techron fuel system cleaners through, she seems to be running a hell of a lot better now. Thank yall