P0204 is an OBD II trouble code. It means that you have a fuel injector with a circuit malfunction, specifically the fourth cylinder in the firing order). It’s generic code, which means that it means the same thing for the Cadillac CTS as it would for any other vehicle.
When the PCM sees that the voltage from cylinder 4 is outside the normal operating range, this code is thrown. P0204 is usually caused by a bad fuel injector or wiring issue. If the misfire were in cylinder 4, you’d get P0203.
P0204 is usually caused by a bad fuel injector or wiring issue.
CTS: P0204 Symptoms
It is rare that there aren’t noticeable symptoms with P0204. Here are the most likely ones:
- Misfire– If your CTS’s fuel injector is not getting the right amount of fuel into cylinder three, it’ll misfire. A misfire will hurt the acceleration of the vehicle and cause fuel mileage to suffer.
- Service Engine Light– The check engine light will obviously be on, but you may or may not get a flashing check engine light at all.
You may also get another code, such as one related to the air/fuel mixture, or a misfire code such as P304 (misfire cylinder four).
P0204 Causes: Cadillac CTS
When diagnosing P0204 in your CTS you only need to look at the fuel injector in cylinder four, since the PCM has pinpointed the location of the problem for you.
1. Bad Fuel Injector
Bad fuel injectors are the most common reason that P0204 is thrown by the PCM. You still want to take a look at the wiring harness. You’ll also want to test the injector. There’s a YouTube video directly above that shows how to do that. A new fuel injector is relatively affordable.
Fuel injectors can make your CTS’s PCM throw P0204 if they are plugged, dirty, or defective.
2. Wiring Issue
When diagnosing P0204, taking a look at the wiring around the injector is a great place to start. You want to make sure that it doesn’t look visibly damaged.
Make sure that the voltage at the injector matches the injectors that aren’t getting the code. If they aren’t that’s a good indication that something is wrong with the wiring harness.
3. Bad PCM
This is the last place that you’d want to look, but a bad PCM can be the reason why your CTS is getting P0204.
Conclusion: P0204 Cadillac CTS
It’s usually not too hard to track down P0204, thanks to the fact that it is specific to the fourth cylinder. If there is anything you would like to add that could help the next person with their CTS, please leave a comment. Good luck!