P0171 – Fuel System Too Lean Bank 1 (Dodge / Chrysler)

Randy Worner

By Randy Worner (Contact Me)
Last Updated 2020-12-14
ASE/ACA World Class Technician

CodeFault LocationProbable Cause
P0171 Fuel System Too Lean Bank 1
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Intake/exhaust leak, AIR system, MAFNAF sensor, fuel pressure/pump, injector(s), HO2S

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What Does Code P0171 Mean?

This generic powertrain/engine diagnostic trouble code typically applies to most manufacturers since 1996. 

This code is focused on the voltage being returned by the Oxygen Sensor (O2S) to the engine controller (ECM/PCM). The PCM monitors the voltage and the sensor’s ability to send both a low voltage (typically below 2.5V) and a high voltage (above 2.5V). If the voltage exceeds a set threshold, never goes above a set voltage, or the voltage does not switch fast enough, a fault code is stored. In this case, the voltage stays low (below 2.5V) for too long a period of time. This can be either an electrical fault (sensor/signal issue) or a mechanical issue (any form of misfire), depending upon the reason for the low O2 sensor voltage being returned.

Where is the P0171 sensor located?

On most Dodge/Chrysler OHC engines the Oxygen Sensor is screwed into the front exhaust manifold. On OHV or Cam-in-Block engines, the Oxygen Sensor is screwed into the exhaust manifold that attaches to the head that has the number cylinder 1 in it. In all cases, the Oxygen sensor that is responsible for this code will be in the exhaust system before the first catalytic converter. 

Typically, the causes for this code to set are:

Most common:

  • Oxygen sensor – O2 sensor signal circuit voltage stuck low/shorted to ground, failed O2 sensor
  • Fuel system components – to include the injectors, fuel pump(s), fuel filter

Less Common Issues:

  • Worn ignition system components, to include the coil, plug wires, spark plugs, etc.
  • (Misfires allows the unburned fuel and air to escape to the exhaust system. Misfires cause O2 voltage to stay low due to high oxygen content coming out of the cylinder.)

Last possibility – Failed PCM – very rarely

What are the common causes of code P0171?

Specific to Chrysler products, these are the more common issues with the Fuel System Too Lean Bank 1 fault code:

  • Dodge Avengers w/2.4L – Fuel pumps and MAF Sensors are the most common issue related to P0171 with cracked exhaust manifolds and O2 sensors a close second.
  • Dodge Avengers w/3.6L – O2 Sensors, and Fuel pumps are the most common issue related to P0171 with Intake Plenum Isolators a close second.
  • Chrysler 300, Dodge Charger/Challenger w/2.7L/3.6L/5.7L – O2 Sensors, and Fuel pumps are the most common issue related to P0171 with injectors and PCM reprogramming / resetting a close second. 
  • Chrysler Minivans w/3.6L – O2 Sensors, and Fuel pumps are the most common issue related to P0171 with Intake Plenum Isolators a close second.
  • Dodge Durango/Dodge Journey/Jeep Wrangler and Grand Cherokee w/3.6L – O2 Sensors, and Fuel pumps are the most common issue related to P0171 with Intake Plenum Isolators a close second.
  • Dodge Dart w/2.0L – O2 Sensors, Injectors, Fuel pumps are the most common issue related to P0171 with gasoline quality and MAP Sensors a close second.
  • Jeep Compass/Patriot w/2.0L or 2.4L – O2 Sensors, Injectors, Fuel pumps are the most common issue related to P0171 with gasoline quality and MAP Sensors a close second.