p0171 system to lean bank one
p0174 system to lean bank two
i just would like to know what i got to do to fix this

2000 tahoe 5.3 Lt

 

either EGR valve O2 and last the Cat

 

Lean bank 1 and 2 mean that both right and left front O2 sensors see to much air to fuel ratio (improper fueling) and the Ecm is compensating for it. Possible causes are bad intake gasket (most likely on 5.3),vac. leak,low fuel pressure or volume,bad air flow meter. You can have a shop smoke check it for vac leaks. It is very unlikely that both o2 sensors are bad. Also a bad egr valve would mostlikely set a EGR insufficient flow code if the valve did not work and if it is stuck open the truck would not idle. If the cat converters are bad you would get a catalist efficency code or possible but rarly a rich code gor rear o2 sensors.If the truck seems to idle funny cold more that likely is intake gasket. Do you have a K&N air filter and did you recently clean and oil it? If oil from filter gets on air flow meter it will mess with the meter. What alot of people do not understand is that codes DO NOT tell you what is wrong, only what is being effected

 

MDTAHOE,
Can you explain what positions the 4 O2 sensor locations are?
I had to replace mine on my97 some years back and it wasn't easy to find what locations were what, i.e. bank 1 sensor 2 is the o2 sensor that is on thepassenger/drivers side,pre/post-cat.
I replaced it and got the correct one but it took some searching to find the correct correlation, even my factory manuals were not clear or at least not easy to decipher.[]

 

Bank 1 is always on the same side as cylinder # 1. Cylinder # 1 is always the side of the engine that the headis further forward. Bank 1 sensor 1 would be the first sensor in the exhaust on cyl. 1 side. Bank 1 sensor 2 would be the second sensor back usually after the cat. Bank 2 is the other side of the engine. Bank 2 sensor 1 is the first sensor and bank 2 sensor 2 would be the next one down the line. The front 2 sensors are used for fuel control and on OBD II cars sensor 2 is mainly used to monitor the cat converter.

 

Thanks!