Workshop Manual

6E–232
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0174 – Fuel Trim System Lean Bank 2
Step Action Value(s) Yes No
1 Was the “On-Board Diagnostic (OBD) System Check”
performed?
— Go to Step 2
Go to OBD
System
Check
2 Are any DTCs set other than P0174 and P0171?
—
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 2 L.T. FUEL TRIM” display on
the Tech 2.
Is the displayed values greater than the specified
values?
L.T. Fuel
Trim: +20%
Go to Step 5 Go to Step 4
4 1. Review and record Tech 2 Failure Records data.
2. Clear the DTC P0171/P0174 and operate the
vehicle to duplicate the Failure Records conditions.
3. Monitor the Tech 2 “DTC” info for DTC P0174 while
operating the vehicle to duplicate the Failure
Records conditions.
4. Continue operating the vehicle until the DTC P0174
test runs.
5. Note the test result.
Does the Tech 2 indicate DTC P0174 failed this
ignition?
— Go to Step 5
The lean
condition is
not present.
If a
driveability
symptom still
exists, refer
to Symptoms
section.
5 Was DTC P0171 also set? — Go to Step 6 Go to Step 15
6 Visually and physically inspect the vacuum hoses for
disconnections, splits, kinks, improper routing and
improper connections and repair any problem found.
Did your inspection reveal a problem requiring repair?
— Verify repair Go to Step 7
7 Visually and physically inspect the crankcase
ventilation valve for proper installation and repair any
problem found (refer to 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
partially block the air flow sample through the MAF
sensor.
2. Correct any problem that is found as necessary.
Did your inspection of the MAF sensor reveal a
condition requiring repair?
— 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 Step 11