Troubleshooting

Detecting Condition and Trouble Area

HINT:
- When DTC P0171 is recorded, actual air-fuel ratio is on LEAN side. When DTC P0172 is recorded, actual air-fuel ratio is on RICH side.
- If vehicle runs out of fuel, the air-fuel ratio is LEAN and DTC P0171 is detected. MIL then comes on.
- Fuel trim applies separately to bank 1 and bank 2, so ECM lights up MIL if a problem occurs with either bank.
- You can tell which bank is malfunctioning by looking at short-term fuel trim and long-term fuel trim, thus allowing you to focus your inspection.
- If total of the short-term fuel trim value and long-term fuel trim value for each bank is within +25%, -25%, the system is functioning normally.




















Inspection Procedure