What causes a U3343 code?

U3343 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 U3343 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with U3343 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.

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OBD-II

U3343

Manufacturer-specific network code U3343

What it means

Data bus performance error. The system detects too many 'error frames' on the communication line, slowing down data transfer.

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