P0171 Ford Explorer
System Too Lean (Bank 1) · Powertrain Code · High · Repair: Moderate
What is P0171?
The engine is running lean on bank 1 — too much air or not enough fuel. Common causes include vacuum leaks, weak fuel pump, clogged fuel injectors, or a faulty MAF sensor.
When the Ford Explorer triggers code P0171 (system too lean (bank 1)), it typically points to an issue in the powertrain system. This is a high severity code, so address it promptly to avoid further damage or safety concerns. Below you'll find the most common causes, symptoms, and repair options specific to the Ford Explorer.
This repair is rated moderate, meaning some experience and specialty tools required.
Diagnostic data on this page is compiled from publicly available repair resources and technical service bulletins. Always have a qualified mechanic confirm the diagnosis before authorizing repairs on your Ford Explorer.
Common Causes on Ford Explorer
- PCV hose or valve failure on 2.3L EcoBoost Explorer/Edge causing vacuum leak
- Charge air cooler pipe clamp loosening from engine movement on 2.3L or 3.5L EcoBoost
- MAF sensor reading low from contamination on 3.3L V6 or 2.3L EcoBoost Explorer
- Intake manifold gasket leak on 3.5L V6 Explorer causing lean condition on bank 1
- Fuel pump driver module corrosion causing low fuel pressure on 2011-2017 Explorer
Symptoms
- Rough or unstable idle speed
- Hesitation or stumble during acceleration
- Engine surging or hunting at idle
- Lean misfire under load causing jerking
- Poor acceleration response and reduced power
- Check engine light illuminated
Notes for Ford Explorer
The 2011-2017 Explorer fuel pump driver module is mounted under the spare tire and prone to corrosion.