I have a 1996 Ford Explorer 2WD XLT 5.0L with check eng lite on. I hooked up a scanner to the OBD. Codes read: P0133 MOD

Article No.
97-15-22
There is a technical service bulletin on these codes. The fix is to have the computor reflashed. Here it is
07/21/97

^ MALFUNCTION INDICATOR LAMP (MIL) - MIL LAMP
ILLUMINATED - DIAGNOSTIC TROUBLE CODES
(DTCS) P0133 AND P0153 STORED IN MEMORY -
EXPLORER WITH 4.0L OR 5.0L ENGINE, AND
MOUNTAINEER WITH 5.0L ENGINE

^ LAMP - MALFUNCTION INDICATOR LAMP (MIL)
ILLUMINATED - DIAGNOSTIC TROUBLE CODES
(DTCS) P0133 AND P0153 STORED IN MEMORY -
EXPLORER WITH 4.0L OR 5.0L ENGINE, AND
MOUNTAINEER WITH 5.0L ENGINE

LIGHT TRUCK:
1996-97 EXPLORER
1997 MOUNTAINEER

ISSUE:

The Malfunction indicator Lamp (MIL) may illuminate with Diagnostic Trouble Codes (DTCs) P0133 and P0153 stored in memory with no driveability concerns present. This may be caused by an interaction with the On-Board Diagnostics (OBD II) Heated Exhaust Gas Oxygen (HEGO) monitor software and the purge vapor management software, and could result in the above listed Powertrain Control Module (PCM) codes.

ACTION:

Reprogram the PCM using the Service Bay Diagnostic System (SBDS) or the New Generation Star (NGS) Tester. The PCM control strategy was revised to prevent a purge "reset" from occurring while running the HEGO monitor. If a reset occurs while running the HEGO test, the strategy now exits the HEGO test. Refer to the following Service Procedure for details.