Broken, shorted, or corroded wiring in the powertrain CAN bus network.
Secondary Air Injection System Incorrect Flow Detected. P1648. 18056. Data Bus Powertrain Malfunction. Customer. JustAnswer Jeep Grand Cherokee Diesel P0700 P1648 Codes Explained p1648-vw
Verify the ECM and TCM are receiving proper voltage and have good grounds. Broken, shorted, or corroded wiring in the powertrain
Check for accompanying codes like P1626 (missing message from TCM) or ABS/TC-related codes. p1648-vw
Using a wiring diagram, check continuity of the high and low CAN Bus wires (usually orange/black and orange/brown) between the TCM and ECM. 4. Typical Fixes
Data Bus Powertrain – Malfunction / No Communication.