DTC P0203 Injector 3 Circuit Fault

Diagnostic Trouble Code (DTC) P0203

Injector 3 Circuit Fault



Circuit Features



  • In this circuit the Engine Control Module (ECM) has four individual injector driver circuits, each of which regulates an injector.
  •  The injector is activated each time the ECM grounds a driver. The ECM regulates the current in each driver circuit.
  •  The ECM is capable of measuring a voltage drop through a fixed resistor and can stabilize it. Strict monitoring is done in order to regulate the voltage on each driver identify a fault.
  •  A Diagnostic Trouble Code (DTC) is boosted in case there is some abnormality in the voltage which the ECM is not expected to note.
  • This DTC is capable of detecting a short to ground and/or an open circuit and short to battery conditions for low-side drive injector outputs.



When will DTC set?


Task boosted after DTC sets

When will DTC clear?

DTC sets when

1) Monitor fault feedback signal from FETS.

1) The ECM will light the Malfunction Indicator Lamp (MIL) the first time the fault is identified.


1) The ECM will turn off the MIL on the third repetitive trip cycle in which the diagnostic has been run and the fault is not there anymore.


2) Engine is in run mode.

2) The ECM will store conditions which were present at the time the DTC was set as Freeze Frame and in the Failure Records data.

2) A history DTC will automatically clear after 40 consecutive warm-up cycles faultlessly.

3) Battery voltage > 9 volts


3) The Scan Tool can be made use of to remove a DTC.

4) Engine speed > 600 rpm (SOHC).



4)  If the ECM battery feed is de-linked for more than 10 seconds.

5)   Engine speed > 700 rpm (DOHC).




6) Fault is present for more than 5 seconds.






Diagnostic Assistance



  • A  DTC P0203 is likely to be set up if there is an injector 2 driver circuit that is open or shorted to voltage.
  • A malfunctioning injector will set a misfire.
  • Ideally a misfire DTC needs to be set indicating mentioning the malfunctioning injector.
  • Abnormally high or low Long-term and short-term fuel trims are a good indication of a malfunctioning injector.
  • Consult "Fuel Injector Balance Test" in this section for details of malfunctioning injectors.
  • You will see that the injector resistance tested at the ECM connection is slightly greater if it is tested directly at the injector as this takes into account the resistance of the harness wires.
  •  The ideal value is about 13.5 ?



Purpose of the test



Number(s) below refer to the step number(s) on the Diagnostic Table.



1-The On-Board Diagnostic (EOBD) System Check assists the technician to finish some routine checks and store the freeze frame and failure records data on the scan tool if applicable. An electronic copy of the data is obtained when the malfunction occurs and this data is then stored on the scan tool for future use.

3-This step is to ensure whether DTC P0203 has been set because of a hard failure or an intermittent condition.

5-In this step the wiring harness is tested along with the ECM control of the injectors using a test light.

7-This step is to see whether the circuitry is shorted to voltage or the ECM is erroneous.

9-The changing of the ECM must be reprogrammed. You need to consult the latest Techline procedure for ECM reprogramming.