P0201

P0201 Injector 1 Circuit Fault




Circuit Description
The powertrain control module (PCM)/engine control module (ECM) has four individual injector driver circuits, each of which controls an injector. When a driver circuit is grounded by the PCM/ECM, the injector is activated. The PCM/ECM monitors the current in each driver circuit. The PCM/ECM measures a voltage drop through a fixed resistor and controls it. The voltage on each driver is monitored to detect a fault. If the voltage is not what the PCM/ECM expects to monitor on the circuit, a Diagnostic Trouble Code (DTC) is set. This DTC detects short to ground and/or an open circuit and short to battery conditions for low side drive injector outputs.

Conditions for Setting the DTC
- Engine is in run mode.
- Battery voltage is greater than 11 volts.
- Above conditions are met for 2.5 seconds.

Action Taken When the DTC Sets
- The PCM/ECM will illuminate Malfunction Indicator Lamp (MIL) the first time the fault is Detected.
- The PCM/ECM will store conditions which were present when the DTC was set as Freeze Frame and in the Failure Records data.
- A history DTC is stored.

Conditions for Clearing the MIL/DTC
- The PCM/ECM will turn the MIL off on the third consecutive trip cycle in which the diagnostic has been run and the fault is no longer present.
- A history DTC will clear after 40 consecutive warm-up cycles without a fault.
- DTC can be cleared by using the scan tool.

Diagnostic Aids
An injector driver circuit that is open or shorted to voltage will cause a DTC P0201 to set. It will also cause a misfire due to an inoperative injector. A misfire DTC should also be set indicating which injector is inoperative.

Long-term and short-term fuel trims that are excessively high or low are a good indication that an injector is malfunctioning. Use Fuel Injector Balance Test to check for malfunctioning injectors.

Injector resistance tested at the PCM/ECM connection is slightly more than if tested directly at the injector because it includes resistance of the harness wires. The normal value is about 13.5 Ohms.

Step 1 - 9:

Step 10 - 11:

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
1. The On-Board Diagnostic (OBD II) System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.
3. This step determines if DTC P0201 is the result of a hard failure or an intermittent condition.
5. This step tests the wiring harness and the PCM/ECM control of the injectors using a test light.
7. This step determines if the circuitry is shorted to voltage or the PCM/ECM is faulty.
9. The replacement PCM/ECM must be reprogrammed. Refer to the latest Techline procedure for PCM/ECM reprogramming.