p1131
Moderate
Ford · SUVs
Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean (Bank 1)
Quick Answer
Error code P1131 on your Ford SUVs means: Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean (Bank 1). This is usually fixable — see the step-by-step guide below.
Affected Models
Applies to all models
BRNCOBRNCSEDGEESCPEEXPDNEXPLREXPLRHBronco Badlands 2024Bronco Base 2024Bronco Big Bend 2024Bronco Raptor 2024Bronco Sport Badlands 2024Bronco Sport Base 2024Bronco Sport Big Bend 2024Bronco Wildtrak 2024Escape Active 2024Escape Platinum 2024Escape ST-Line 2024Expedition King Ranch 2024Expedition Limited 2024Expedition Platinum 2024Expedition XLT 2024Explorer Base 2024Explorer Limited 2024Explorer Platinum 2024Explorer ST 2024Explorer XLT 2024MACHE
Likely Causes
How to Fix It
1
Monitor bank 1 upstream O2 sensor voltage with a scan tool during idle and snap throttle
2
Perform a smoke test to check for vacuum leaks on bank 1
3
Test fuel pressure at the fuel rail under idle and load conditions
4
Inspect exhaust manifold and pipe connections for leaks on bank 1
5
Replace upstream O2 sensor on bank 1 if readings are flat or unresponsive
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
Parts You May Need
Upstream O2 sensor (bank 1)
Vacuum hoses
Fuel filter
Exhaust manifold gasket
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