DEF on injector
Some 2011-2012 Ford F-Super Duty vehicles equipped with a 6.7L diesel engine may exhibit DTCs P1291 and/or P1292 due to an internally shorted fuel injector. An internal short in a fuel injector may be caused by the fuel being contaminated with DEF (diesel exhaust fluid) or by fuel gelling.
Remove the fuel conditioning module mounted filter. Allow the filter and filter bowl to dry for two hours. If the filter and/or filter bowl turns white, the concern was caused by the fuel being contaminated with DEF. The high pressure fuel system and diesel fuel control module will need to be replaced.
If the filter/filter bowl did not turn white, inspect the engine wiring harness for wire chafing near the EGR cooler.
Disconnect each fuel injector’s electrical connector for DTC P1291 at fuel injector 1, 4, 6 and 7 and/or DTC P1292 at injectors 2, 3, 5 and 8. Check for continuity between the injector electrical pins and the injector body. If continuity is not present, refer to Powertrain Control/Emissions Diagnostics manual for normal diagnostics.