Service Engine Code 174

[jmac]

The "service engine soon" light has come on in my wife's 2002 Yukon denali. I took the vehicle to Autozone where it registered Code 0174, Fuel trim bank two condition. Causes are

1. Bank one and two are set together suspect fuel condition or Maf fault.

2. Failed HO2S21

3. Ignition misfire condition

4. Fuel injector problem

5. Engine mechanical condition

 

The car is running just fine.

Things I have done.

1. Added fuel system cleaner

2. Changed fuel filter

3. Cleaned MAF

 

The service engine light went off the next day after I performed all above. Well after my wife filled up a week later it immediately came on again.

 

I replaced the O2 sensors and fuel pump last year. Also I am not sure what HO2S1 refers to.

 

What do you guys think could be causing the code? thanks

[VR021302]

The "service engine soon" light has come on in my wife's 2002 Yukon denali. I took the vehicle to Autozone where it registered Code 0174, Fuel trim bank two condition. Causes are

1. Bank one and two are set together suspect fuel condition or Maf fault.

2. Failed HO2S21

3. Ignition misfire condition

4. Fuel injector problem

5. Engine mechanical condition

 

The car is running just fine.

Things I have done.

1. Added fuel system cleaner

2. Changed fuel filter

3. Cleaned MAF

 

The service engine light went off the next day after I performed all above. Well after my wife filled up a week later it immediately came on again.

 

I replaced the O2 sensors and fuel pump last year. Also I am not sure what HO2S1 refers to.

 

What do you guys think could be causing the code? thanks

 

I believe its heated O2 sensor 1. I wonder if u got some bad gas. I will never again use grocery store gas, or sam's club gas either. They both have given my vehicles problems.

[62handler]

HO2S21- heated O2 sensor Bank 2 sensor 1 (pre-cat)

 

first thing is to look for a vaccume leak, easiest way is to smoke test the intake, other wise listen for an air leak (a stethascope helps), or you can spray some carb clean and listen for an idle change, that dosent work to well with a small leak and can actually swell a gasket up so it dosent leak anymore and hide your problem. look closely anywhere a hose connects to the intake and follow all the hoses to where the end up. look for cracked hoses, make sure that your intake pipe from the airbox is on tight. look arround the base of the intake, these motors are know for intake gasket leaks.

 

an exhaust leak before your O2S can cause a false lean code, or a faulty O2S could be to blame as well.

 

without a scanner with data stream its going to be dificult to diagose this problem

[joshua214]

the h02s1 is the sencor befor the cat on mos trucks i hade that problem with my 96 gmc jimmy check that one and replace it

[silveradobobby]

HO2S21- heated O2 sensor Bank 2 sensor 1 (pre-cat)

 

first thing is to look for a vaccume leak, easiest way is to smoke test the intake, other wise listen for an air leak (a stethascope helps), or you can spray some carb clean and listen for an idle change, that dosent work to well with a small leak and can actually swell a gasket up so it dosent leak anymore and hide your problem. look closely anywhere a hose connects to the intake and follow all the hoses to where the end up. look for cracked hoses, make sure that your intake pipe from the airbox is on tight. look arround the base of the intake, these motors are know for intake gasket leaks.

 

an exhaust leak before your O2S can cause a false lean code, or a faulty O2S could be to blame as well.

 

without a scanner with data stream its going to be dificult to diagose this problem

 

 

I second this info! If had scan tool could tell you fast what it is! Without parts changing to find the problem!