Affected models:
911 Carrera (996)/1911 Carrera 4 (996), as of model year 2002

In vehicles produced before the date of introduction stated above, the Check Engine warning light may be activated by an error in the diagnostic software of the DME control module. The OBD II system registers a malfunction of the oxygen sensor and activates the Check Engine warning light, even though the oxygen sensor is fully operational.

One of the two following malfunction codes is stored in the DME control module’s fault memory:
P2096 — Signal delay time for oxygen sensor aging — above limit; or
P2098 — Signal delay time for oxygen sensor aging, Bank 2 — above limit.

For vehicles with this problem, the PST2 (Porsche System Tester 2) or the PIWIS Tester must be used to delete the fault memory and reprogram the DME control module with new DME software. The PST2 or the PIWIS Tester is required to have the software version 22.0 or higher. The oxygen ­sensors in vehicles with this defect are fully functional and do not need to be replaced. No further repairs are required.

Note: To program the DME control module, the “DME programming code” and the “immobilizer code” need to be known (see IPAS After Sales Service).

Introduction:
Introduction of the new DME software on Jan. 12, 2004, as of the following VINs: 99 54S 62 1761 USA; 99 94S 65 1984 USA; and 99 84S 63 5157 USA.

Work Procedure:
Program the DME control module with the new software version.

Caution: The programming operation must not be interrupted. The battery must be connected to a suitable battery charger. If there is an interruption due to a voltage drop while programming, malfunctions in the DME control module cannot be ruled out.

1. Connect the battery to a battery charger.
2. Connect the PST2 (or PIWIS Tester) with software version 22.0 or higher to the diagnostic plug and switch it on. The procedure for the PST2/PIWIS tester is identical.
3. Switch on the ignition.
4. Using the PST2, select “Control Module Search” in the Control Modules menu.
5. Select the DME control module from the Control Modules selection and open the fault memory.
6. If there are any additional malfunctions stored apart from the two related to this bulletin, they must first be localized and eliminated.
7. After remedying the faults and deleting the fault memory, continue with step 8.
8. Program the DME control module according to the specifications of the 911 Carrera (996) Technical Manual, Group 2, Chapter 24 70 19.
9. Using the PST2, select “Control Module Search” in the Control Modules menu. Fault memory entries (CAN DME time-out or the like) in the control modules that are due to the DME programming must be deleted. Read out fault memory again and localize and eliminate stored malfunctions.
10. After remedying the faults and deleting the fault memory, continue with step 11.
11. Change to the PST2 start menu, switch off and disconnect the PST2.
12. Switch off the ignition.
13. Disconnect the charger.

Courtesy of ALLDATA.