DTC | P1638 | Microcontroller Malfunction |
An ECM ROM (A) malfunction is detected by using a checksum technique for verifying data. Digital data is composed of zeros and ones. A checksum is the total of all ones in a string of data. By comparing the checksum value with a stored value, a malfunction can be detected.
DTC No | Detecting Condition & Limp Home | Suspected area |
P1638 | Detecting Condition Internal operating fault on ECM Software fault on injector operating system Communication fault between microcontrolller and output transistor Communication fault between gate arrays Enable Condition Ignition switch : ON Limp Home None (Engine stop or limit of fuel quantity) | - ECM |
● Internal fault. There is no inspection of service possible for this diagnostic trouble code. ● Cancel the fault memory and perform test drive. ● If the fault cannot be cancelled, temporarily install a good ECM and check for proper operation. |
