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6E–214 6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS DTC P0171 – Fuel Trim System Lean Bank 1
Step Action Value(s) Yes No 1 Was the “On-Board Diagnostic (OBD) System Check” — Go to Step 2 Go to OBD System Check 2 Are any DTCs set other than P0171 and P0174? — Go to the applicable DTC charts and repair the other DTCs before proceeding with this chart Go to Step 3 3 1. Start the engine and operate the vehicle in “closed loop”. 2. Observe the “BANK 1 L.T. FUEL TRIM” display on the Tech 2. Is the displayed value greater than the specified value? L.T. Fuel Trim: +20% Go to Step 5 Go to Step 4 4 1. Review and record the Tech 2 Failure Records data. vehicle to duplicate the Failure Records conditions. 3. Monitor the Tech 2 “DTC” info for DTC P0171 while operating the vehicle to duplicate the Failure 4. Continue operating the vehicle until the DTC P0171 test runs and note the test result. Does the Tech 2 indicate DTC P0171 failed this — Go to Step 5 The lean condition is not present. If a driveability symptom still exists, refer to Symptoms section. 5 Was DTC P0174 also set? — Go to Step 6 Go to Step 15 6 Visually and physically inspect the vacuum hoses for Did your inspection reveal a problem requiring repair? — Verify repair Go to Step 7 7 Visually and physically inspect the crankcase Crankcase Ventilation System). Did your inspection reveal a problem requiring repair? — Verify repair Go to Step 8 8 1. Inspect the MAF sensor inlet screen for damage or for the presence of foreign objects which may 2. Correct any problem that is found as necessary. Did your inspection of the MAF sensor reveal a — Verify repair Go to Step 9 9 Start the engine and note the idle quality. Is a high or unsteady idle being experienced? — Go to Step 10 Go to Step11 10 1. Visually and physically inspect the throttle body, intake manifold, EGR valve and the EGR feed pipe 2. Repair any vacuum leaks as necessary. Did your inspection reveal a vacuum leak? — Verify repair Go to Step 11 |