MIL Service Engine Soon Telltale is Illuminated With DTCs P0171 and/or P0174

Some customers may comment about the (MIL) SERVICE ENGINE SOON telltale being illuminated with DTC(s) P0171 - Fuel Trim System Lean Bank 1 and/or DTC P0174 - Fuel Trim System Lean Bank 2 may be set and stored in ECM memory.

This condition may be caused by insufficient torque on the intake manifold vacuum chamber bolts. Under deceleration, enough vacuum can be created inside the intake manifold to lift the vacuum chamber off it's seal creating an intermittent vacuum leak.

Refer to the service procedure in this bulletin to retorque the intake manifold vacuum chamber bolts.

Notice: When servicing intake manifold do not use power tools. Damage to threads or manifold may occur.

1. Loosen clamp at air cleaner assembly and throttle body assembly.
2. Remove attachment bolts from outlet resonator/duct assembly.
3. 3. Remove outlet resonator/duct assembly.



4. Remove outlet resonator/duct assembly bracket from manifold.



5. Remove 16 (10 around outside, 6 on inside) intake manifold top cover bolts and cover.



6. Remove vacuum chamber and apply Loctite 242® P/N 21485277 (or equivalent) (in Canada, P/N 12345382) to the bolts and reinstall.
7. Torque vacuum chamber bolts according to torque sequence shown.

Tighten
Tighten the Vacuum Chamber-to-Intake Manifold Bolts 2.5 N·m (22 lb in)




8. Ensure sleeve seals are in position on manifold top cover and install cover into position.
9. Apply Loctite® 242 P/N 21485277 (or equivalent) to all 16 top cover bolts and hand start.
10. . Torque 10 bolts around outside of cover as shown.

Tighten
Tighten the 10 Outside Intake Manifold Top Cover-to-Manifold Bolts 4 N·m (35 lb in)




11. Torque 6 bolts on inside of cover as shown.

Tighten
Tighten the 6 Inside Intake Manifold Top Cover-to-Manifold Bolts 4.4 N·m (39 lb in)




12. Install outlet resonator/duct assembly bracket to intake manifold.

Tighten
Tighten the Outlet Resonator/Duct Assembly Bracket-to-Intake Manifold Nuts 5 N·m (44 lb in)




13. Install outlet resonator/duct assembly into position.
14. Tighten clamp at throttle body assembly.
15. Position outlet resonator/duct assembly to support bracket and install bolts.

Tighten
Tighten the Outlet Resonator/Duct Assembly-to-Support Bracket Bolts 10 N·m (89 lb in)

16. Tighten clamp at air cleaner assembly.
17. Verify Repair as follows:
18. Connect Scan Tool to the vehicle.
19. Navigate to the 3.0L (VIN B) menu.
20. Select DIAGNOSTIC TROUBLE CODES (DTC)
21. Select CLEAR DTC INFORMATION, this will zero the short and long term fuel trim information.
22. Navigate to the Powertrain Menu and Select DATA DISPLAY
23. Select ENGINE DATA DISPLAY
24. Select FUEL AND EMISSIONS
25. Monitor the following data:

•	Short Term FT Bank 1

•	Short Term FT Bank 2

26. Start the engine, the Short Term FT will remain at 0% until the vehicle enters closed loop operation (approximately 5 seconds). Does the Short Term FT Bank 1 or 2 exceed 5% during the first 10 seconds of closed loop operation? (After 10 seconds the Short Term FT readings can be affected by EVAP canister purge vapors)

•	If yes, there is still a lean condition present, refer to DIAGNOSTIC AIDS for P0171/P0174 in the 2002 VUE Powertrain Electrical Diagnostics Service Manual.

•	If no, vehicle is repaired.

21485277 - Loctite® 242 Threadlocker (in Canada, use P/N 12345382)

To receive credit for this repair during the warranty coverage period, submit a claim through the Saturn Dealer System for J5520 (Inlet Air Control Vacuum Reservoir - Replace), or if another procedure is performed, refer to the appropriate Electronic Labor Time Guide for the correct Labor Operation Code and Time.