Codes 171 & 174, Aurora 03 4.0 v8, 123k - Aurora Oldsmobile Cars & Trucks

Fuel system too lean.

PCM software needs to be updated

Vacuum leaks (Intake Manifold Gaskets, vacuum hoses, PCV hoses, etc.)

Mass Airflow Sensor (MAF)

Plugged Fuel Filter or weak Fuel Pump

Plugged or dirty Fuel Injectors

Common Misdiagnosis would be a faulty o2 sensor

You did not list a vehicle, so here are the generic codes.
Code 171 is system lean bank one and code 174 is system lean bank two.
The computer is getting a signal from the O2 sensors saying the fuel system is too lean, and the computer can not make it rich.
Possible causes are low fuel pressure, vac leaks, EGR valve problems, and so on.

Hello, symptoms of a faulty Camshaft Position Sensor can include hard starting (or no starting), rough running/misfiring and/or loss of power.

Code 340 COULD be caused solely by a faulty Camshaft Position Sensor. However, this code refers to the entire circuit. So, replacing the sensor may not fix the issue. The problem could lie in any part of the circuit - the sensor itself, the wiring, or the PCM.

Codes 171 and 174 typically appear together. They are caused by the 02 sensors reading too much air (lean) in the exhaust. In most cases, simply cleaning the MAF sensor does the trick. I typically take it off and spray it with electronics or brake cleaner. Just make sure it dries before reinstalling. If this doesn't eliminate the codes, inspect all vacuum and PCV hoses, check for a dirty fuel filter and ensure the furl pressure is within limits.

For clarification, the first trip to the shop your car showed codes 402, 732, 733, 171 and 174. After changing the DPFE/EGR, did ALL those codes go away and now only codes 340, 171 and 174 exist? Or do you have the second set of codes in addition to the first codes?

Thanks

Try some injector cleaner in order to see if the lean condition improves. Lean conditions can sometimes be caused by o2 sensors or other sensors that are not within specifications.

171 and 174 mean it is running lean and 300 means a random cylinder misfire

did they ever reflash the ecm with the new codes for the motor

171 system to lean bank one, 174 to lean bank 2, 300 multiple miss fire,316 crank sensor defective. Does it run rough? Replace crank sensor first.

switch, we run off snitches. 171 174 banks 1 & 2 Lean. Most likely cause are Upper Intake Manifold Gaskets, failed seals. It's not 1990 on. It's 1996 and on OBD2.

ford has a technical service bullitin out on this vehicle for the intake gaskets leaking causing a vacum leak that set codes 171 174. the solution is to have the intake manifold gaskets replaced . call your local ford dealer and see what thay can tell you about this bullitin.

first check out for o2 sensor if its faulty this can show up.but if its proper.Evaporative emission control system leak very small 171 System too lean (bank 1) 174 System too lean (bank 2)