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Code 171 and 174 are for bank 1 and 2 running too lean. The engine has compensated as rich as it can go, and it is still to lean. This does not necessarily mean your mixture is bad, but something (a sensor) is telling the ECM to correct lean. The oxygen sensors alert the ECM to how lean/rich the exhaust is, and then the ECM trips a code. Maybe you have a bad oxy. sensor, but since there are 4 of them (2 per bank), I don't think they could all go at once.
Check for loos connections between the intake and the tube from the air filter. Check if the clamp is loose or leaks in the tube which can cause an incorrect reading. Other than that it may be a dirty MAF sensor which can be fixed by spraying carb cleaning or tuner spray in the intake or it may be bad or a bad oxygen sensor;.
PO 134 = 02 SENSOR CIRCUIT NO ACTIVITY DETECTED (BANK 1 SENSOR1)
PO 153 =02 SENSOR CIRCUIT SLOW RESPONSE (BANK 2 SENSOR 1)
PO 154 =02 SENSOR CIRCUIT NO ACTIVITY DETECTED (BANK 2 SENSOR 1)
PO 155= 02 SENSOR HEATER CIRCUIT MALFUNCTION (BANK 2 SENSOR 1)
PO 171= SYSTEM TOO LEAN (BANK 1)
PO 174= SYSTEM TOO LEAN (BANK 2)
I WOULD SAY YOU HAVE FAULTY OXYGEN SENSORS CAUSING THE ENGINE TO RUN TOO LEAN REPLACE THEM AND YOU SHOULD BE BACK IN BUISNESS
Thes code 171 nad 174 are bank 1 and bank 2 system to lean(02 sensors). these are probably causing the 420 catalist efficency below threshold. The first place to start is all the vacuum lines. check for vacuum leaks. when you get the first two codes 99% of the time it is a vacuum leak. 1% is the mass air flow meter/sensor. And I don't believe you have one on your truck. to old. Also you have to check for vacuum leaks around the intake manifold. use WD40 , spray around the manifold gasket areas if the engine runs better you found a leak.
P0171------ system too lean bank#1
Po174------ system too lean bank#2
For these 2 codes, try cleaning the maf sensor (mass air flow), that is mounted in the big black hose that goes from the air filter housing to the throttle plate, if it is dirty, that will cause those 02 sensors to send a signal to the computor to lean the air fuel mixture. If cleaning it doesn't work, the sensors will probably need changing.
P0300---- Random/multiple cylinder misfire
P0316---- Cylinder misfire at start up---- first 100 revolutions.
On those 2 codes, you have to do some testing to find out why there is a misfire.
weak coil pack
fowling spark plugs/wires
Low fuel pressure
oxygen sensor failure P0171 System too Lean (Bank 1) - Read Our Article On Oxygen Sensor Codes For Help With This Generic Check Engine Light Code P0174 System too Lean (Bank 2) - Read Our Article On Oxygen Sensor Codes For Help With This Generic Check Engine Light Code
hope this is a bit of a push in the right direction ...