OBII COMPUTER SAYS CHECK ENGINE LITE IS ON DUE TO CODE PO174

code p0128 indicates a mechanical fault ( could be the thermostat stuck open)
code p0174 -system too lean -bank2 ===causes --intake /exhaust leak--fuel pressure/pump--injectors--AIR system--hose connection/s
code po171 refers to system too lean bank 1 same as po174 with the HO2S sensor being the culprit. As to all being related . only by way of the o2 sensors
code p0442 is not connected to the first 3 as it is in a different section of the fuel system

PO174- too lean bank two --is a possible rich
condition driven lean by the pcm

Check for leaking injectors,vacuum leaks,fuel pressure

Look at fuel trim on scanner

The front oxygen sensors get replaced every 100,000 miles,
so there may be some of the problems

Start with fuel trim,cylinder misfires,spark plugs, injectors, on that
bank, as a place to do your testing for the code

Look at freeze frame data & I/M Monitor activity, to see if the O2
Monitors ran clean & look at O2 data

Lean bank 1 and bank 2 , and throttle actuator system fault. Check reason for lean codes 1st, vacuum leak(s), air inlet boot and hoses, or low fuel pressure / clogged filter. Repair as needed then clear codes and recheck .

Google --- OBD2 your veh & the code

Can't learn anything by someone telling you

Read it & Study

Description : The adaptive fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. Now that we have an Idea of what the codes mean , we need to narrow them down. More than likely the problem is causing both codes to set. Keeping this in mind, lets concentrate on Code PO1309. Of the possible causes listed above I see two Sensors that may throw up a lean code. I would look at the MAF Sensor first and then the Temp Sensor. You may find that if you remove the internal Sensor from the MAF Case that some degree has collected on the thin wire. If you find debree, use a Q-Tip to clean it. DO NOT USE CHEMICALS TO CLEAN IT. If no debree is found, try a Known Good MAF Sensor. Still no fix, move on to testing the rest of the Sensors on the list till you find the problem. Keep in mind that the check engine light will have to be cleared after you have fixed the problem.

Description : The adaptive fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. Now that we have an Idea of what the codes mean , we need to narrow them down. More than likely the problem is causing both codes to set. Keeping this in mind, lets concentrate on Code PO1309. Of the possible causes listed above I see two Sensors that may throw up a lean code. I would look at the MAF Sensor first and then the Temp Sensor. You may find that if you remove the internal Sensor from the MAF Case that some degree has collected on the thin wire. If you find debree, use a Q-Tip to clean it. DO NOT USE CHEMICALS TO CLEAN IT. If no debree is found, try a Known Good MAF Sensor. Still no fix, move on to testing the rest of the Sensors on the list till you find the problem. Keep in mind that the check engine light will have to be cleared after you have fixed the problem.

CODE PO172 - SYSTEM ADAPTIVE FUEL TOO RICH BANK 1 POSSIBLE CAUSE EVAP VAPOR RECOVERY SYSTEM FAILURE MAY BE PULLING VACUUM.FUEL PRESSURE REGULATOR FAULTY.HO2S ELEMENT CONTAMINATED.LEAKING FUEL INJECTORS. CODE PO174 - FUEL SYSTEM TOO LEAN CYLINDER BANK 2. POSSIBLE CAUSE EXHAUST LEAKS BEFORE OR NEAR THE HO2S,WEAK FUEL PUMP.RESTRICTED FUEL INJECTORS, LEAKING EGR VALVE GASKET OR DIAPHRAGM.MAF SENSOR DIRTY CAUSING PCM TO UNDERESTIMATE AIRFLOW.

Description : The adaptive fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. Now that we have an Idea of what the codes mean , we need to narrow them down. More than likely the problem is causing both codes to set. Keeping this in mind, lets concentrate on Code PO1309. Of the possible causes listed above I see two Sensors that may throw up a lean code. I would look at the MAF Sensor first and then the Temp Sensor. You may find that if you remove the internal Sensor from the MAF Case that some degree has collected on the thin wire. If you find debree, use a Q-Tip to clean it. DO NOT USE CHEMICALS TO CLEAN IT. If no debree is found, try a Known Good MAF Sensor. Still no fix, move on to testing the rest of the Sensors on the list till you find the problem. Keep in mind that the check engine light will have to be cleared after you have fixed the problem.

those codes are for lean engine condition look for vac leaks at the back of engine to the pcv valve could hear hissing noise with engine running also check egr valve to be stuck open also when was last fuel filter changed? hope this helps .