What causes a P170F code?

P170F 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 P170F code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P170F 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

P170F

UNSPD NOx sensor overrun diagnostic

What it means

This code indicates that the NOx sensor signal is 'overrunning' or lagging behind the expected values during transient engine operations, signaling that the sensor is no longer responsive enough to provide accurate emissions data.