What this code means
P0201 may indicate a problem in the cylinder 1 fuel injector circuit.
What the vehicle may do
- The engine may run rough.
- The vehicle may feel uneven under load or at idle.
- A misfire-like symptom can occur when injector control is not correct.
Possible fault areas
- A possible fuel injector concern.
- A possible injector power or control circuit concern.
- A possible connector or harness condition.
- A possible relay power or PCM-related concern.
Diagnostic path
Opening and code focus
On this 6.2 liter Super Duty, P0201 may point to a cylinder 1 fuel injector circuit problem. The truck may run rough, misfire, or feel uneven because the PCM may not be able to control that injector the way it expects. The broad possible areas are the injector itself, the injector power or control wiring, connector condition, relay power, or the PCM. Start with the basic system checks and follow a structured diagnostic approach. If other codes are present, check what they mean first. For P0201, stay on the individual injector diagnostic path and do not jump into the relay branch unless the codes actually lead you there.
Check for other codes before circuit testing
With P0201 confirmed, crank the engine, turn the ignition ON, and check for BCM DTCs. On some vehicles, injector circuit faults may show up with BCM fuel pump relay codes or PCM fuel-system-related codes. If those are present, handle those first. If they are not present, move into the cylinder 1 injector circuit checks.
Verify injector power feed
Turn the ignition OFF and disconnect the suspect fuel injector connector. Only the suspect injector needs to be diagnosed here. Turn the ignition ON and measure voltage at VPWR Pin 2 at the injector connector. On some vehicles, injector voltage is only there while the fuel pump relay is energized, so make that measurement within 2 seconds of the ignition ON. If voltage is greater than 10.5 V, keep going. If it is not, repair the open circuit, clear the PCM DTCs, and repeat the self-test.
Check the injector control circuit for an open
Next, turn the ignition OFF, disconnect the PCM connector, and check the injector control circuit for an open. For P0201, measure resistance between INJ Pin 1 at the injector connector and INJ1 Pin E39 at the PCM connector. If resistance is less than 5 Ω, continue. If it is not, repair the open circuit, clear the PCM DTCs, and repeat the self-test.
Check for short to ground and short to voltage
Now check the same injector control circuit for a short to ground at INJ Pin 1 at the injector connector. If resistance is greater than 10000 Ω, move on. If it is not, repair the short circuit, clear the PCM DTCs, and repeat the self-test. Then turn the ignition ON and check INJ Pin 1 for voltage. If any voltage is present, repair the short to voltage, clear the PCM DTCs, and repeat the self-test. If no voltage is present, continue to the injector resistance check.
Check injector resistance
With the ignition OFF, measure resistance through the fuel injector on the component side between VPWR Pin 2 and INJ Pin 1 at the injector connector. The injector should measure between 11 Ω - 18 Ω. If it is in that range, keep diagnosing the circuit operation. If it is outside that range, install a new fuel injector, reset KAM, and repeat the self-test.
Check injector driver command with a test lamp
Reconnect the PCM connector, turn the ignition ON, and connect a non-powered test lamp between VPWR Pin 2 and INJ Pin 1 at the injector connector. Crank the engine. If the lamp blinks, the circuit is being commanded and the next move is to look for an intermittent harness issue. If the lamp does not blink, go to the PCM connector and module-operation check.
Wiggle test when the circuit works
If the test lamp blinks, turn the ignition OFF, reconnect the injector connector, then turn the ignition ON and monitor the INJ_F Status PID. Wiggle, shake, and bend small sections of the harness while working from the injector back toward the PCM. If injector values fluctuate in and out of range, isolate the area and repair it as needed, then clear the PCM DTCs and repeat the self-test. If nothing changes and the concern cannot be duplicated, pause there, recheck the earlier diagnostic path, and avoid guessing.
Relay branch when the codes point there
If the scan results lead you into the injector relay side of this test, start by carrying out the injector relay component test. If the relay does not pass, install a new injector relay, clear the PCM DTCs, and repeat the self-test. If the relay passes, turn the ignition OFF, disconnect the injector relay connector, turn the ignition ON, and measure B+ voltage at Pin 2,3 at the injector relay connector. If voltage is greater than 10.5 V, keep going. If it is not, repair the open circuit, clear the PCM DTCs, and repeat the self-test.
Finish the relay circuit checks
With the ignition OFF, disconnect the PCM connector and check the relay circuits for an open. Measure resistance between INJRLY Pin 1 at the injector relay connector and the INJRLY circuit at the PCM connector, and also between VPWR Pin 5 at the injector relay connector and INJPWRM Pin E48 at the PCM connector. If resistance is less than 5 Ω, continue. If it is not, repair the open circuit, clear the PCM DTCs, and repeat the self-test. Next, check for a short to ground between INJRLY Pin 1 and VPWR Pin 5 at the injector relay connector. If resistance is greater than 10000 Ω, turn the ignition ON and check for a short to voltage between those same relay connector pins. If any voltage is present, repair the short circuit, clear the PCM DTCs, and repeat the self-test. If no voltage is present, move to the PCM connector and module-operation check.
PCM connector and operation check when command is missing
If the test lamp does not blink, or the relay branch sends you here, check for correct PCM operation. Disconnect all PCM connectors, inspect for pushed out pins and corrosion, then reconnect all PCM connectors and make sure they seat correctly. Verify whether the concern is still present. If it is still present after that connector check, install a new Powertrain Control Module and complete the required programming. If the concern is gone, the system is operating correctly at this time, and the issue may have been caused by a loose or corroded connector.
Repair verification and takeaway
Keep verification separate from testing. After any circuit repair, injector replacement, connector correction, relay replacement, or module repair path, clear the PCM DTCs and repeat the self-test to confirm P0201 stays gone. The takeaway is simple: prove power, prove the control wire, prove the injector, then prove command and connector integrity before condemning the module. For more diagnostic training, visit stepdiagnostics.com.
Final check
P0201 is often approached as an electrical injector circuit diagnosis: verify the related codes first, then prove power, circuit integrity, injector resistance, command, and connector condition in a
For more guided automotive diagnostics, visit STEP Diagnostics.
