OBD code P0300 is a diagnostic trouble code that indicates random (or multiple) misfires in your Cadillac CTS's engine cylinders. It's a generic trouble code, meaning that it applies to all relevant makes & models sold in the US.
Diagnostic code P0300 is a "catch-all" for engine cylinder misfires when the PCU either doesn't know which cylinder is experiencing the issue or when it needs to let you know about multiple cylinders misfiring.
Codes close to p0300 but with a different final digit like P0302 indicate the same issue but include information on what cylinder experienced the misfire. That is to say, if you get a P0302, that means you're looking at a cylinder 2 issue.
Symptoms Associated with P0300
Some of the primary symptoms related to trouble code P0300 on the Cadillac CTS include
- The engine being difficult to turn over & start
- A stumbling / hesitating response when the engine is running.
Causes for P0300 on the Cadillac CTS
The most common cause of P0300-related issues is a problem with spark plugs & the associated wiring. Oxygen (O2) sensors & fuel injectors also make up a sizable portion of P0300 triggers.
Other issues that cause P0300 misfires more infrequently include Exhaust Gas Recirculation (EGR) leaks, defective PCU issues, or even issues with your catalytic converter.
How to fix P0300 on a Cadillac CTS
If you're not noticing any issues besides the check engine light, your best bet it probably to just reset the code & see what happens. If it keeps coming back, then it's time to look into a repair.
If the engine is hesitating or not as alert as it seems it should be, check spark plug wiring & the spark plugs themselves. Depending on the age of your iginition parts, you could do worse than to replace them as a regular maintenance practice.
Specific parts to consider replacing here include your distributor cap & your spark plugs (& associated wiring). One other consideration might be that your catalytic converter has given up the ghost. Get a whiff of your exhaust – and see if you can smell rotten eggs. If you do, you're probably in for an expensive catalytic converter replacement.
We recommend buying from Amazon & installing it yourself or handing the part over to an expert.
When fixing P0300, it goes a long way to have an advanced scan tool to track down misfires. We recommend BlueDriver as the standout favorite for home & professional use here.
Check out Scotty Kilmer's Video on code P0300.
Scotty Kilmer is a wiz at this stuff & his youtube videos are an easy way to get back up & running. Once you've read the content above, we recommend giving him a listen too