What this code means
P0201 may indicate a fuel injector control circuit problem on the affected cylinder, often involving the circuit the engine control module uses to command that injector.
What the vehicle may do
- The vehicle may run rough or misfire.
- The MIL may come on or flash if a misfire is occurring.
- The engine control module may disable the affected injector when it detects a circuit condition.
Possible fault areas
- Possible injector high control circuit issue.
- Possible injector low control circuit issue.
- Possible connector or harness issue.
- Possible fuel injector electrical fault.
- Possible engine control module driver concern.
Diagnostic path
Opening and code context
On this 2014 to 2018 GMC Sierra 1500 with the 5.3 gas engine, P0201 points us toward a possible fuel injector control circuit problem on the affected cylinder. The truck may run rough, misfire, set the MIL, or disable that injector when the engine control module sees a circuit fault. Broadly, we’re thinking about the injector itself, the high and low control wiring, connector issues, or a possible ECM driver concern. The key is not to guess at the injector first. Work the circuit in order.
Start with checks and monitor gates
Start with the basic system checks, then follow a structured diagnostic approach before getting into pinpoint testing. For this fault, the ECM supplies voltage on the injector high control side and turns the injector on by grounding the low control side. If the ECM detects the injector control circuit is open for greater than 2 s, shorted to ground for greater than 2 s, or shorted to voltage for greater than 2 s, it can set P0201 and disable the affected injector. For the monitor to run, ignition voltage has to be greater than 11 V.
Initial verification
With the ignition ON, first make sure the ECM injector-control-related code is not set. If that code is present, deal with what it means before continuing this injector circuit path. If it is not set, let the engine idle. The engine has to be running for the injector control circuit status parameters to work. On the scan tool, the injector control circuit status parameters should show OK or Not Run. For this episode, pay close attention to the cylinder 1 injector status, since we’re focused on P0201.
Reproduce the fault before teardown
If the scan tool status is OK or Not Run, reproduce the operating conditions for the DTC. You can also reproduce the captured conditions if the failure data gives you a clue. Then confirm whether P0201 resets. If it does not reset, the circuit checks out at that moment. If the injector status does not show OK or Not Run, or the code resets during the drive condition, move into circuit testing.
Check for a short to ground
For circuit testing, turn the ignition OFF, make sure all vehicle systems are OFF, and disconnect the X3 harness connector at the engine control module. Give the vehicle time to go fully asleep; it may take up to 2 min for all vehicle systems to power down. Now test for infinite resistance between the appropriate fuel injector high control circuit and ground. If it is less than infinite resistance, disconnect the fuel injector connector and test that high control circuit to ground again. If it still reads less than infinite resistance, repair the short to ground in that circuit. If the high control circuit is now infinite, test the low control circuit to ground. Less than infinite resistance there means repair the short to ground in that circuit. If both sides are infinite at that point, the path leads you back to testing or replacing the fuel injector.
Check for a short to voltage
If the first high-control-to-ground resistance test was infinite, turn the ignition ON and check voltage between the fuel injector high control circuit and ground. You are looking for less than 1 V. If you see 1 V or greater, disconnect the fuel injector connector with the ignition ON and check that high control circuit again. If it is still 1 V or greater, repair the short to voltage on that circuit. If it drops to less than 1 V after unplugging the injector, repair the short to voltage on the low control circuit.
Check circuit continuity and resistance
If the voltage test is less than 1 V, turn the ignition OFF and test resistance between the fuel injector high control circuit and low control circuit. The expected result is less than 10 Ω. If it is 10 Ω or greater, disconnect the injector connector and check the circuits end to end. The high control circuit should be less than 2 Ω. If it is 2 Ω or greater, repair the open or high resistance in that circuit. If the high side is less than 2 Ω, test the low control circuit end to end. That should also be less than 2 Ω. If it is 2 Ω or greater, repair the open or high resistance in that circuit. If both end-to-end checks are less than 2 Ω, the next step is to test or replace the fuel injector. If the high-to-low circuit resistance was already less than 10 Ω, the path is to test or replace the engine control module.
Component testing the injector
For component testing, turn the ignition OFF and disconnect the connector at the affected fuel injector. For an accurate measurement, ECT needs to be between 10–32°C (50–90°F). Measure resistance between the injector terminals. The specification is 1.06 Ω +/− 10% @ 20°C (68°F). If it is not within that range, replace the fuel injector. If it is within range, test for infinite resistance between each injector terminal and the injector housing or case. Less than infinite resistance means replace the fuel injector. Infinite resistance means the injector passes those checks.
Intermittents and final verification
If the fault is intermittent, move the related harnesses and connectors with the engine running while watching the injector control circuit status on the scan tool. A change from OK or Not Run to Malfunction tells you the circuit or connection is reacting. Also remember, high resistance in an injector circuit may show up as a misfire without setting an injector circuit code, and the MIL flashes when there is an engine misfire. After any repair, verify the repair and confirm the code stays gone.
Takeaway
The takeaway on P0201 is simple: prove the circuit before condemning parts. Check the scan data, then separate shorts to ground, shorts to voltage, opens, high resistance, injector resistance, and the ECM path in that order. For more diagnostic training, visit stepdiagnostics.com.
Final check
P0201 is best approached as an electrical circuit diagnosis where the injector, wiring, connectors, and ECM control path all need to be proven in order.
For more guided automotive diagnostics, visit STEP Diagnostics.
