What causes a P151E code?

P151E 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 P151E code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P151E 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

P151E

DEFOI urea severe fault (4th threshold)

What it means

DEFOI Urea Severe Fault (4th Threshold) indicates that the aftertreatment system has reached the final level of inducement due to a persistent DEF system failure.