Service Engine Soon (SES) Telltale Illuminated with Diagnostic Trouble Codes (DTCs) P0171, P0172, P0174 and/or P0175 (Refer to Diagnostic Procedure in this Bulletin, Replace Mass Air Flow (MAF) Sensor

This bulletin is being revised to include DTC's P0172 and P0175 as well as the addition of 2002 and 2003 model years. Please discard Corporate Bulletin Number 01-06-04-016 (Section 06 -- Engine), Saturn Bulletin Number 01-T-17.

Some customers may comment that the SES telltale is illuminated.

This condition may be caused by one or more of the following: debris on MAF sensor causing an incorrect reading, improper oil level, low or high fuel pressure, Engine Control Temperature (ECT) Sensor reading inaccurate, EVAP system problem and/or poor fuel quality.

Follow current Service Manual Diagnostic Information for DTC's P0171, P0172, P0174 or P0175. If long term fuel trim values approach DTC limits, follow the procedure outlined in this bulletin for additional diagnosis and MAF sensor replacement.

1. For lean DTC’s, check for vacuum leaks due to damaged or loose intake manifold switchover valve vacuum lines mis-routed, missing O-ring located between the intake manifold lower section and the intake manifold upper section and correct if necessary. For rich DTC’s, check EVAP purge solenoid for sticking open. Verify ECT sensor is providing accurate temperature for proper engine fuel metering.



2. Check for proper engine oil level.

•	If oil level is correct, proceed to next step.

•	If oil level is too high, perform the following:

-	Drain oil to correct level.

-	Clean oil from throttle body and air tubing leading to oil separator.

-	Replace MAF sensor. (Refer to step 5.)

3. Check fuel pressure by performing "Fuel System Pressure Test". Refer to "Fuel System Diagnosis" (SI Document ID #1094549 [2000], 1073922 [2001 and 2002] or 1241266 [2003]) in the Fuel System section located in the applicable Saturn L-Series L81 Engine Service Manual.

•	If fuel pressure is correct, proceed to next step.

•	If fuel pressure is out of specification, diagnose by performing "Fuel System Testing" (SI Document ID #1149744) for 2000-2002 or "Fuel System Diagnosis" (SI Document ID #1241266) in the Fuel System section located in the applicable Saturn L-Series L81 Engine Service Manual.

4. Check fuel quality. If poor fuel quality is suspected, drain tank and refill with known good fuel and recheck fuel quality.



5. If the above checks in steps 1-4 are OK, replace MAF sensor, P/N 90528435. Refer to "Mass Air Flow (MAF) Sensor Replacement" procedure (SI Document ID #1073998) located in the applicable Saturn L-Series L81 Engine Service Manual.

To receive credit for this repair during the warranty coverage period, submit a claim through the Saturn Dealer System using the appropriate Electronic Labor Time Guide and labor operation code J5670 (Sensor, Mass Air Flow - Replace) or if another procedure is performed, refer to the appropriate Electronic Labor Time Guide for the correct labor operation code and time.