What is course of action for PO171, PO174 and P1153

Tiny
ROYCAR71
  • MEMBER
  • 1998 GMC JIMMY
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 149,900 MILES
I recoverd 3 codes. PO171, PO174. And P1153. What would be my first course of action? Thanks.
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Tuesday, October 28th, 2014 AT 3:26 AM

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Tiny
CARADIODOC
  • EXPERT
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.
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Tuesday, October 28th, 2014 AT 4:34 AM
Tiny
ROYCAR71
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I know its been a year or so ago from this topic. After checking for are leaks, cleaning mass air flow sensor, and replacing all 3 o2 sensors. I was able to drive around nearly few months without receiving this code. Now all of sudden it has popped up again. I noticed in past during hotter temps the code was recurring. Yesterday while driving in over 100 degrees temperture and drive for over hour codes comes on. Could this be an over heating problem as well?
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Saturday, June 13th, 2015 AT 5:41 AM
Tiny
CARADIODOC
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If only the "lean" codes came back, you also might look at the EGR valve if your engine has one. That is a common cause of intermittent code 171 on Fords. The next thing would be to connect a scanner to view live data so you can see exactly what the oxygen sensors are reporting. The front ones should be switching between "rich" and "lean" about two times per second. Your mechanic can introduce forced rich and lean conditions to see if the oxygen sensors respond properly.

By the way, you listed a 4-cylinder engine. How can you have "lean" codes on two banks, left and right?
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Tuesday, June 16th, 2015 AT 1:43 AM

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