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Buick ECM

This bulletin applies to 2018 Buick Enclave, 2017-2018 LaCrosse and 2018 Regal vehicles. Some customers may comment that the MIL is on. The technician may find DTC P0459 (evaporative emission purge solenoid valve control circuit high voltage) set in the ECM as active or history.

This condition may be caused by an interaction between the ECM and purge solenoid that can cause the DTC to set under certain conditions. The condition may be more noticeable in colder climates.

1. Follow the diagnostic procedure for DTC P0459 in th4e service manual.

2. Validate the EVAP purge solenoid and/or circuit performance. If issues are found, refer to the service manual for repair and inspect the ECM’s Julian date. If no issues are found, inspect the ECM’s Julian date.

3. An ECM with a Julian date between 1A18053 17 074 XXXX (March 15, 2017) and 18 046 XXXX (Feb. 15, 2018) is to be replaced. The new ECM is available as P/N 12687296.

The first two characters in the red box are the year (A) and the next red box is the Julian date (B) that corresponds to a day of the year. The last 4 numbers are a unique sequential number built that day.
<p>The first two characters in the red box are the year (A) and the next red box is the Julian date (B) that corresponds to a day of the year. The last 4 numbers are a unique sequential number built that day.</p>

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