Viermalvier.de, das Geländewagenportal Foren Marken talk Reisemobile auf US 4x4 Basis F-350 Fehler Code P0271

First, a little lesson as the codes can tell you what to look for. The FICM controls power and ground for the injector coils by activating drivers for the power and ground circuits for the injectors. The FICM measures the current on each circuit to determine if an injector coil is open or shorted.

Open injector coils and open injector coil power or ground circuits produce low current which sets injector circuit low codes

Shorted injector coils or shorts to ground on the injector coil power circuits produce high current which sets injector circuit high codes

In this case, the DTC P0270 indicates that injector #4 is not drawing the expected amount of electrical current when actuated. Since a low current condition exists we know that there is an open in a circuit somewhere. It could be EITHER power or ground circuit on EITHER coil, the open coil or the close coil. This includes the harness, both coils, and the FICM itself. My experience is that a single injector low code typically ends up being the injector and a harness issue the next likely cause. It is rare that a FICM would cause a single injector low DTC and I recall seeing that maybe once or twice over the years.

You can disconnect the harness at the suspect injector and measure the resistance of each coil to determine if they are electrically open. Measure between pins 1 and 2 for the open coil and pins 3 and 4 for the close coil. A typical reading is about 0.8 to 1.0 ohms which is in the middle of the specs. You can find pin numbers on the face of the connector molded into the plastic and they are very small. A light and a magnifying glass might help you read them. If either coil does not meet specification the injector is bad and needs to be replaced. If the coils test good then you need to test the harness circuits. If those test good the FICM is suspect.