DTC P0171, DTC P0172, DTC P0174 Or DTC P0175: Notes

WARNING: This page is about a different car, the 2003 Toyota Tundra. However, it is still accessible from the selected car via links, so may be relevant.

Code Definition

DTC P0171: System Too Lean (Bank 1)
DTC P0172: System Too Rich (Bank 1)
DTC P0174: System Too Lean (Bank 2)
DTC P0175: System Too Rich (Bank 2)

CAUTION: If Engine Control Module (ECM) replacement is instructed in following test, always ensure ECM electrical connectors and ground circuits are okay. If either are defective, repair and repeat testing to confirm ECM malfunction.

NOTE: If the vehicle runs out of fuel, the air-fuel ratio is LEAN and DTCs P0171 and P0174 are recorded. The MIL then comes on.

NOTE: When DTCs P0171 and P0174 are recorded, the actual air-fuel ratio is on the LEAN side. When DTCs P0172 and P0175 are recorded, the actual air-fuel ratio is on the RICH side.

NOTE: If the total of the short-term fuel trim value and long-term fuel trim value is within + or - 25 percent, the system is functioning normally.