Hello,

I have a 99 Suburban K2500 with a 454 with 185k miles, and I cannot seem to get rid of my P0175 code. About 11 months ago when I bought the truck, I replaced spark plugs, fuel injectors, pressure regulator, fuel filter, and fuel pump. A few months later, I started getting codes for 02 senors. I replaced both downstream and both upstream, and the codes cleared for awhile. I did need to replace the upstream twice as the first two I got were both defective. Now, it has been several months, and I still get the P0175 code for bank 2. This is the only code I get. I also find it strange that the code comes and goes. My CEL will be on for about two weeks, then it will shut off for awhile and then turn back on.

I have also replaced the EGR valve with one from another vehicle and my MAF seems to function fine, with no rough idle or loss of power.

Any suggestions? I am pulling my hair out with this one!

 

if its flex fuel...not sure if they had that in 99 on a 2500....reset the sensor reading. if its value is skewed it makes the fuel trim rich.

 

I do not think it is flex fuel. When you mention resetting the sensor, can you elaborate, please? I am unsure of what sensor you are meaning.

 

older flex fuel vehicles have a sensor to measure the OH content of the fuel. with a scan tool you can view the % of OH the vehicle is measuring. Most pump gas is 10%....if the sensor is skewed and reading higher than it really is....it changes the fuel metering and the result is a rich fuel trim. with the scan tool reset the fuel trim and reset the OH sensor value.

if you do not have a ff vehicle....check the fuel pressure and make sure its not high.
view the freeze frame data...if the fault set at idle.... if you have a vacuum fpr...make sure the vac line is attached and has vac at idle.

 

MAF can be off but not enough to set a code. I had that in a Malibu, ran fine most of the time.
I fought a bad MAP in my '11 5.3 . Lost 3-4 mpg due to it. It didn't set any codes but it affected my fuel mileage. Look at your STFT, should run / vary between -5 to +5 . The closer the 0 the better.

P0175 CHEVROLET code possible causes

• Faulty front heated oxygen sensor
• Ignition misfiring
• Faulty fuel injectors
• Exhaust gas leaks
• Incorrect fuel pressure
• Faulty Mass Air Flow (MAF) sensor