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MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS MULTIPORT FUEL INJECTION (MFI) 13A-264 13A DTC P0171: System too Lean (bank 1) . CIRCUIT OPERATION • Multiplicative or Additive adaption performed by ENGINE-ECU. . TECHNICAL DESCRIPTION • If a malfunction occurs in the fuel system, the fuel trim value becomes too large. • The ECU checks whether the fuel trim value is within a specified range. . DTC SET CONDITIONS Check Conditions • Bank 1 too lean Judgment Criteria • MIL on after 2 drive cycles. • No limp home. . EOBD DRIVE CYCLE PATTERN Refer to Diagnostic Function − EOBD Drive Cycle − . . TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:) • Injector (Number 1, 3, 5) malfunctioning. • Incorrect fuel pressure. • Air drawn in from gaps in gasket, seals, etc. • Use of incorrect or contaminated fuel. • Refer to component locations GROUP- • Refer to configuration diagrams GROUP- • Refer to circuit diagrams GROUP- DIAGNOSIS Required Special Tools: • Diagnostic Tool (MUT-III Sub Assembly) • MB991824: V.C.I. • MB991827: USB Cable • MB991910: Main Harness A STEP 1. Check for intake system vacuum leak. Q: Are there any abnormalities? YES : Repair it. Then go to Step 4. |