Codes PO203 and 303

Welcome to 2CarPros.

The codes you listed, P0202 and P0303 are separate. The 202 is a cylinder two injector issue and 303 is a misfire (cylinder three). Now, what I suggest is this. I am going to attach a flow chart for testing the injector. You can follow that to identify the cause of the code. However, what I suggest is this. Switch the cylinder two and three injectors with two other cylinders. Once you do that, clear the codes and run the vehicle to see if the trouble codes change to different cylinders. It they do, then replace the injectors.

If you look at pictures 1 and 2, they are a flow chart of what to check.

Also, here are a few links that may be helpful:

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

https://www.2carpros.com/articles/how-to-replace-a-fuel-injector

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring

Let me know what you find or if you have other questions.

Take care,
Joe

You are exactly right! Sorry about that. However, I would still try switching the injector. In this case, the injector P0203 is most likely causing the P0303. It could just be a bad injector. If the code changes to a different cylinder when you make the change, then we know it's the injector.

Or, you could test the injector for resistance to see if it is good. Here is the resistance it should have:

Output Actuator Injector
Coil resistance. 13 - 16 Ohm at 20°C (68°F)

The only thing I can say is it must be related to the ECM. It is what supplies the power to each injector. See attached schematic.

You can drive it, but it will have a misfire. If it is dumping fuel, it can cause damage to the catalytic converter. As far as the ECM, something must have shorted out internally and allowing 12 v to get sent to that injector.

Hi:
I attached the wiring schematic for the injectors, control module, and power supplies. I had to break the schematic into two parts because of size. I did overlap them so you can continue following them.

If you look at pictures 3 and 4, that shows the ECM pin layout. Picture 4 shows which pins are responsible for the injectors. I would check those pins at the ECM to confirm the variation on voltage. If you find it at the ECM, something inside if has shorted.

If it needs reprogrammed, I recommend a dealer to do it.

Let me know if this helps.

Joe