Nissan cold start DTCs

his TSB applies to 2008-2010 Nissan Altima vehicles equipped with the QR25DE 4-cylinder engine. For a 2008-2009 Altima, DTC P1421 (cold start control) may be stored in the ECM. For a 2010 Altima, DTC P050E (cold start control) may be stored.

Refer to Step 2 in the Service Procedure to confirm that this bulletin applies. If this bulletin does apply, reprogram the ECM.

1. Connect the CONSULT PC to the vehicle to begin the reprogramming procedure.
2. When you get to the ECM Reprogramming screen, confirm that this bulletin applies as follows:
1. On your C-III screen, look at the Part Number column. If this column is blank (no part number listed), this bulletin does not apply. Close C-III and refer to ASIST for further diagnostic information. If a part number is listed, write it on the repair order.
2. Compare the part number that you wrote down to the numbers in the Current ECM Part Number column. If there is a match, this bulletin applies. Continue with the reprogramming procedure. If there are two lines (two reprogramming options) on your C-III screen, use the one that does not have the message “Caution! Use ONLY with NTBXX-XXX.” If there is not a match, this bulletin does not apply. Close C-III and refer to ASIST for further diagnostic information.

3. If this bulletin applies and you have performed ECM reprogramming, the screen in the following Figure 1 appears when reprogramming is complete.
4. Make sure to erase DTCs from all systems (during reprogramming, DTCs will set in several systems and must be erased).
5. Test drive the vehicle for proper operation and verify that the MIL is off.