P0171 - System too Lean (Bank 1)
P0174 - System too Lean (Bank 2)
P1153 - O2 Sensor Heater Circuit High Voltage (Bank 2 Sensor 1)
I'd start by checking the wires going to the passenger side front oxygen sensor. Look for two or more that are melted together, and for signs of corrosion between the pins in the connector. A break in a wire is also a good suspect.
Lean codes for both sides of the engine are often the result of a vacuum leak. Check the fresh air tube between the mass air flow sensor and throttle body for cracks or loose clamps. Any air that sneaks in there that doesn't go through the mass air flow sensor won't be measured, and the Engine Computer won't command the right amount of fuel to go with it.
A misfiring spark plug will send unburned fuel and air into the exhaust system, but it's only the oxygen that will be detected as a lean condition. That will typically only show up on one side of the engine, not both.
Tuesday, October 28th, 2014 AT 4:34 AM