Cadillac ATS P0496 OBDII Code Diagnosis

P0496 Cadillac ATS

One of the most common trouble codes with the Cadillac ATS is the P0496 code. This code number references a number that is given to you when you plug your ATS into an OBDII scanner.

Below, you’ll find the most common symptoms and ways to diagnose the P0496 in your Cadillac ATS. Good Luck!


Cadillac ATS P0496 Symptoms

Here are the most common symptoms of P0496:

  • Erratic Idle– P0496 code in the Cadillac ATS will often be accompanied by an erratic idle. The engine will rev up and down trying to find the proper idle speed. This will often happen right after you buy gas. It also might not start at all at the gas station.
  • Fuel Smell– There may be a noticeable fuel smell right after filling up.
  • Service Engine Soon– More often than not, the only symptom of P0496 will be the OBDII trouble code itself.

If you’re old enough to have driven a carbureted vehicle the old stomp the gas and crank the engine method does actually help start the vehicle. This is due to the air fuel mixture being off.
Related: P0420 Cadillac ATS


Cadillac ATS P0496 Meaning

P0496 is a universal OBDII trouble code. This means that regardless of which make or model of vehicle, the code will mean the same thing. The code technically stands for:


Cadillac ATS P0496 Diagnosis


The EVAP system captures all fuel vapor from the fuel tank and sends them to the engines intake in order to be ignited in the normal combustion process.

When the Cadillac ATS computer detects that the EVAP system is purging when it should not be, it will throw the P0496 OBDII code.


Cadillac ATS P0496 Causes

There are many things that can cause the P0496 trouble code on the Cadillac ATS. Here are the most common problems that will throw the code.

  • Vapor Purge Valve– The most common culprit with the P0496 trouble code and the Cadillac ATS is going to be the vapor canister purge valve. When it goes bad, it typically causes issues with the vehicle’s idle speed. This is especially true right after you fuel up the vehicle. It’s really easy to replace. There are a few clips that you need to find and remove. There is a a great YouTube video on diagnosing the problem below.
  • PCM– It is possible that the engines computer system itself has gone bad and is registering a P0496 when it shouldn’t be. This is is definitely not where you want to start.
  • Wiring– It is possible for shorts in the wiring harness leading to the Vapor Canister Purge Valve has gone bad. Check it. Here’s a good article on diagnosing a short in a vehicle.
  • Fuel Cap– A bad fuel cap can cause the P0496 code to be thrown for sure. Often, you’ll get a message informing you that the fuel cap is off even when it is on. If you are getting that message, plus a P0496 on your Cadillac ATS, it may save you a ton of time and money to replace the fuel cap and see if it goes away.
  • Fuel Tank Pressure Sensor– If the fuel tank pressure sensor has gone bad, it can cause all sorts of problems, including the P0496 code.

Here’s a good video on it:


A mechanic can do a smoke test to determine exactly where the leak is coming from. If you have a hard time figuring it out, it’s pretty easy to do the test.



Good luck figuring out what is wrong with your ATS. We hope this helps. If there is anything that you feel like you could add, please feel free to leave a comment below.