Engine codes

[daldyc]

The check engine lite is on. The OBD2 reader is showing P0171,,P0174,, .Banks 1 and 2 are lean.Anyone have any ideas.Fuel economy and power haven't changed.Its a 02 vue with a 3.0 engine

[fdryer]

Just a guess but it may be a possible mass air flow (MAF) sensor becoming faulty that would affect the engine or a manifold leak common to both cylinder banks. If there's a manifold leak then it may be a simple procedure to find the leak using carb spray in and around the intake manifold/throttle body area; the vacuum leak will draw in the spray and change the idle speed almost immediately, indicating the source of the vacuum leak. There are many gaskets and rubberized couplers to check that may be the cause of a lean mixture. Try reading up on the threads, with or without the search feature, about the L300's MAF sensor and Vue MAF sensors as they share the same 3.0 liter engine. Early L300's were prone to MAF failures (keeping my fingers crossed) but not on a regular basis. Hope this helps. :cool:

[WifesVUE]

FWIW, I just had 171, 172 and I think 174 on our '03. On the second visit, they replaced one of the oxygen sensors. The technician performed tests similar to those listed in the previous post while monitoring the voltage levels. He determined the sensor was responding too slowly.

[IMkenNY]

This is the most likely cause. It took ~ an hour to repair my Vue and these codes never came back..




(MIL) Service Engine Soon Telltale Illuminated With DTCs P0171 and/or P0174 (Retorque Intake Manifold Vacuum Chamber Bolts, Install Vacuum Chamber Springs) #02-06-01-016A - (Mar 24, 2003)


(MIL) SERVICE ENGINE SOON Telltale Illuminated With DTCs P0171 and/or P0174 (Retorque Intake Manifold Vacuum Chamber Bolts, Install Vacuum Chamber Springs)
2002-2003 Saturn VUE -- Built Up To and Including VIN Breakpoint 3S854417

with 3.0L, V6 Engine (VIN R -- RPO L81)

Technician

This bulletin is being revised due to a change in Parts Requirements. Please discard bulletin 02-T-28 (Corporate Bulletin Number 02-06-01-016 , Section 06 -- Engine).

Condition
Some customers may comment on the (MIL) SERVICE ENGINE SOON telltale being illuminated. (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 the ECM memory.)

Cause
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.

Correction
Refer to the service procedure in this bulletin to retorque the intake manifold vacuum chamber bolts and install the vacuum chamber springs.

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

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

Remove outlet resonator/duct assembly.

Remove outlet resonator/duct assembly bracket from manifold.

Remove 16 (10 around outside, 6 on inside) intake manifold top cover bolts and cover.
Remove vacuum chamber and apply Loctite™ 242, P/N 21485277 (in Canada, P/N 12345382), or equivalent, to the bolts and reinstall.

Torque vacuum chamber bolts according to torque sequence shown.

Torque
2.5 N·m(22 in-lbs).

Install vacuum chamber springs, P/N 93175463, on vacuum chamber as shown.
Ensure sleeve seals are in position on manifold top cover and install cover into position.
Apply Loctite™ 242, P/N 21485277 (in Canada, P/N 12345382), or equivalent, to all 16 top cover bolts and hand start.

Torque 10 bolts around outside of cover as shown.

Torque
10 Outside Intake Manifold To Cover-to-Manifold Bolts 4 N·m(35 in-lbs).


Torque 6 bolts on inside of cover as shown.

Torque
6 Inside Intake Manifold Top Cover-to-Manifold Bolts: 4.4 N·m39 (in-lbs).

Install outlet resonator/duct assembly bracket to intake manifold.

Torque
Outlet Resonator/Duct Assembly Bracket-to-Intake Manifold Nuts: 5 N·m(44 in-lbs).

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

Torque
Outlet Resonator/Duct Assembly-to-Support Bracket Bolts: 10 N·m (89 in-lbs).

Tighten clamp at air cleaner assembly.
Verify Repair as follows:
- Connect Scan Tool to the vehicle.

- Navigate to the 3.0L (VIN B) menu.

- Select DIAGNOSTIC TROUBLE CODES (DTC).

- Select CLEAR DTC INFORMATION, this will zero the short and long term fuel trim information.

- Navigate to the Powertrain Menu and Select DATA DISPLAY.

- Select ENGINE DATA DISPLA.

- Select FUEL AND EMISSIONS.

Monitor the following data:
- Short Term FT Bank 1

- Short Term FT Bank 2

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 2002-2003 VUE Powertrain Electrical Diagnostics Service Manual.

- If no, vehicle is repaired.