What causes a P1699 code?

P1699 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 P1699 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P1699 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

P1699

Voltage reference 4 maximum range fault

What it means

The engine control module (ECM) provides several 5-volt reference signals to various sensors. P1699 indicates that the specific circuit designated as 'Reference 4' is receiving voltage higher than the expected 5V range.