P1601 - FAULT CODE - OBD2

P1601 BUICK, CADILLAC, CHEVROLET, GMC: SERIAL COMMUNICATION MALFUNCTION

Serial Peripheral Interface (SPI) communication is used internally by the Engine Control Module (ECM). Through this, data is sent between the engine processor and the automatic transmission processor. A message checksum is included in each of the messages sent between the two processors. This value is compared with the calculated checksum. If some inconsistencies are discovered, the processor will check the new data and define it as corrupt and ignore the value. After this, the processor uses the previous message to notify the last message is corrupted.

The ECM often monitors the periodic status message from the TCM. If the message is not received, the fault counter has increments, and the P1601 OBDII fault code will be set.

• Check Engine light ON.

Reasons to set the P1601 OBD2 DTC P1601 code:

• There may be damage to the ECM or TCM wiring or electrical connections.
• The ECM may have programming errors.
• The ECM may be faulty.

Steps to troubleshoot the P1601 OBDII diagnostic code:

• First, we recommend that you consult the An advanced diagnosis is necessary to avoid unnecessary replacements due to the complexity of the P1601 code.
• Perform an on-board diagnostic (EOBD) system check. If you find inconsistencies in the EOBD system, make the appropriate repairs.
• Check if there are any additional DTCs If this is the case, diagnose the codes following the order shown in the tool.
• Verify that the ECM electrical connections and wiring are not defective due to water, burns, or wear. Fix if necessary.
• If only the P1601 code is set, it is necessary to diagnose the ECM. For this purpose, we recommend you visit a specialized automotive center because it will be necessary to reprogram or replace the ECM.