What causes a U0636 code?

U0636 can be triggered by several issues — see the verified probable causes and step-by-step diagnostics shared by mechanics and owners on OBDIY.

Can I drive with a U0636 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with U0636 active.

Follow the step-by-step diagnostic on this page, then read the verified fixes contributed by other Heavy Truck owners — the answer marked "Verified Cause" worked for the original poster.

OBDIY

OBD-II

U0636

Network/CAN bus communication code U0636

What it means

Communication lost with the fuel pump control module. The engine control module is unable to send or receive data from the fuel pump controller via the CAN bus.