2004 Silverado 1500 4.3L Running Rich! P0175
 

2004 Chevy Silverado 4.3L v6 Truck is running rich, when put on a scan tool, shows P0175, so took off 02 sensors and cleaned them, did not help, took off the spark plugs, all clean, no signs of wetness. Takes 4-12 seconds to turn the truck over, at 40 MPH the truck makes rumbling sounds and on start up the exhaust will sometimes make a dim popping sound and it sounds like it doesn't want to keep running when first started. 4 out of 6 plug boots were straight and the other 2 were L shaped, I bought it as is, and I don't know if that had anything to do with it.

Maf sensor is good also.

P0175 OBD-II Trouble Code

Technical Description

System Too Rich (Bank 2)

What does that mean?

Basically this means that an oxygen sensor in bank 2detected a rich condition (too little oxygen in the exhaust). On V6/V8/V10 engines, Bank 2 is the side of the engine that doesn't have cylinder #1.

Note: This DTC is very similar to P0172, and in fact your vehicle may show both codes at the same time.

Symptoms

You will more than likely not notice any drivability problems, although there may be symptoms such as a misfire.

Causes

A code P0175 may mean that one or more of the following has happened:

The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters can cause the MAF to become dirty if the filter is over-oiled
There could be a vacuum leak.
There could be a fuel pressure or delivery problem
Possible Solutions

Possible solutions include:

Inspect all vacuum and PCV hoses, replace if necessary
Clean the MAF sensor. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
Inspect fuel lines for cracks, leaks, or pinches
Check the fuel pressure at the fuel rail
Check the fuel injectors, they may be dirty. Use fuel injector cleaner or get them professionally cleaned/replaced.
Check for an exhaust leak before the first oxygen sensor (this is unlikely to cause the problem, but it is possible)

The OBD-Codes.com guy who wrote this article missed the point. P0175 alone can't be all those. A single bank rich condition (low oxygen content in the exhaust) without O2-sensor-specific trouble codes usually means a defective O2 sensor or leaky or imbalanced fuel injector(s).

Re: P0175
 

It's possible the O2 sensor is sending a false rich command to the computer, in which case you will need to replace the O2 sensor.