Truck Trend Garage: 2001 Dodge Durango Runs Rich
Question: I have a 2001 Dodge Durango 4x4 with the 4.7-liter and an automatic transmission. I received code 171, replaced both oxygen sensors, and checked the vacuum system and catalyst. The code remains and the truck is running rich and producing rich exhaust.
| 2001 Dodge Durango Front View
Answer: Trouble code P0171 indicates a lean condition, and replacing both oxygen sensors (assuming you don't have four) eliminates them from the scenario. A poor connection in an O2 circuit is still possible. When an oxygen sensor sends an incorrect "lean" signal to the Powertrain Control Module, the PCM will send a "rich" command to the injectors to compensate. But there are several other items that can produce a true lean condition. Top of the list is fuel pressure, which needs to be tested with an accurate fuel pressure gauge. It may be a bad pump, or a restriction due to a clogged filter or in-tank strainer. Contaminated fuel is also a possibility. After that you need a scan tool to evaluate incoming sensor data, such as improper TPS, ECT, or MAP signals. And, of course, it can be some other hard-to-find stuff like a hidden vacuum leak, mechanical engine problems, a faulty PCM, or poor connections in the wiring to and from the PCM.
If you have a technical question regarding your pickup, SUV, or van, feel free to contact Alex, a master technician with the National Institute for Automotive Service Excellence. Send a letter to him in care of Truck Trend Garage, 831 S. Douglas Street, El Segundo, CA 90245, or e-mail us at trucktrend@sourceinterlink.com. Please include the VIN with your question. Due to the volume of questions received every month, we cannot guarantee that everyone's question will be personally answered or will appear in the magazine.
Can't wait for help with a problem you're having with your Truck or SUV? Ask the expert we trust here at Truck Trend Garage -- visit Alex Steele at www.RealWorldAutomotive.com.
