P0171 & P0174 Sputtering Uphill

Hello everyone! I have a 2015 Tacoma with 9k miles on it. A while ago it threw the P0171 and P0174 codes. It only seems to have trouble when the truck has less than a quarter tank of gas and especially going up hill. I have already replaced the MAF sensor and the Air filter. I'm thinking that it might be a blocked fuel filter or a faulty fuel pump. Thoughts, ideas ? Thanks.

 

Most likely fuel pump.

Mine failed with 50K miles on the clock. Pathetic. Check fuel pressure, if it's low, you'll need to replace it.

 

Take it to the dealer and let them sort it out. Warranty.

 

I'll have to figure out how to check the fuel pressure. I'm currently stationed overseas in Sicily, not sure if there is a dealership out here.

 

Hey many years ago.. Like in '95. I was in a similar situation in Germany with a Dodge Ram 1500 I had purchase through AAFES. I called them explained and they got me in touch with warranty people and I was able to take it to a local shop. Toyota may not Be as agreeable and I guess it depends where you bought it.

 

Below is what the Service Manual says about your codes and what to check:

I would also check the fuel pressure first as your statement about 1/4 tank and going up hills. It could be a lot of simpler and cheaper fixes also. Always start work from simple and cheap to expensive and complex.

DTC No.:

P0171
P0174

DTC Detection Conditions:

With warm engine and stable air-fuel ratio feedback, fuel trim considerably in error to lean side (2 trip detection logic)

Trouble Areas:

• Air induction system
• Injector blockage
• Mass Air Flow (MAF) meter
• Engine Coolant Temperature (ECT) sensor
• Fuel pressure
• Gas leakage from exhaust system
• Open or short in A/F sensor (bank 1, 2 sensor 1) circuit
• A/F sensor (bank 1, 2 sensor 1)
• A/F sensor heater (bank 1, 2 sensor 1)
• A/F sensor heater relay
• A/F sensor heater and A/F sensor heater relay circuits
• PCV valve and hose
• PCV hose connections
• ECM

 

I have a 2007 tacoma v6 4x4 which also sets same codes randomly and lose engine power usually going up hill or under load for 3 to 10 seconds then runs fine for quite awhile . Never know when it is going to quit. I checked all that I knew how and ordered a new pump today . Will let you know how I make out.

 

It's odd than in the service manual above that it never mentions a possible bad pump as a possibility

 

That would fall under fuel pressure but yes manufacturer flow charts are generally crap other than sometimes giving code set criteria and direction on things to check.

 

This is an update on my problem. Ordered a new fuel pump assembly and had my local mechanic install in tank and all though I haven't put many miles on it since ,I am confident my intermittent problem is repaired. I just took old pump assy apart and the filter/screen was very dirty and appeared to be nearly clogged. Thanks to the other person who posted similar symptoms and repairs that corrected his problem