How To Fix P0499 Obd2 Code?

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How To Fix P0499 Obd2 Code
Table of Contents

Code p0499 can happen because of various reasons. So, you need to find the exact cause before you take the necessary actions to fix the problem!

Many times people misdiagnose the error code and replace the perfectly working evaporative emission control system. Instead of that, one needs to pay attention to the fuel cap, fuel leaks, or check if all the parts are properly installed or not. 

The error code is a mild issue and will never affect the working of your vehicle. You can read the article and know what actually this code is, how to resolve this issue or the ways you can follow to avoid it in the future!

Definition Of P0499 Codes

In case, if the scanner has diagnosed the p0499 code, it means that your ECM has detected an inadequate amount of pressure in evaporation emission system. Or, in simple words, you can say that the code shows that there is a fault in the evaporation emission control system. 

The general function of an evaporation emission control system is to capture all the vapors of the fuel before they get escaped and get entered the atmosphere. 

So, to run the system smoothly all the vapors are collected and then passed through the canister of charcoal. The activated charcoal actually keeps all the vapors stored before passing them out through the inlet tract.

Definition Of P0499 Codes

The vent valve and charcoal canister both work in collaboration. The function of these two is to let the fresh outside air get in, which then combines with an EVAP system and helps in displacing the fuel vapors.

The vent valve usually remains open, and a current of 12-volts usually closes the valve. Well, this happens only when Powertrain Control Module has to pressurize the EVAP system t check if there is any leakage. So, a mild issue in the vent valve control circuit or vent valve store the code, and warning lights appears!

Error Code P0499: Symptoms, Causes & Fix

Symptoms Of P0499 obd2 Codes

You may not face any drivability issues but the most obvious and common sign you may notice is a check engine light. And, this sign can also appear due to multiple other codes as well. Therefore it is pretty important to completely inspect your car to find the root cause of the P0499 code. (P0730 Obd2 Code).

You must check all the wiring connections, find damaged wiring, fuel system and a visual inspection will let you know the cause of this fault code. 

There are multiple other common mistakes that users made, therefore check the vehicle’s operation completely. though it will be an extremely difficult and tiring procedure you have to do it!

Causes Of P0499 obd2 Code

The code can appear because of multiple reasons, but the most common reason is the pressure in the evaporation emission system vent valve control circuit. And, this happens when you do not properly attach the fuel cap and as a result, the scanner diagnoses the P0499. 

In addition, the following are the other reason for this trouble code: 

  • A defective or faulty purge control solenoid (so never forget to check the purge condition)
  • Error in the pressure sensor 
  • A blocked or clogged charcoal canister could also be a probable cause of this faulty code
  • Burnt, damaged, or corroded wiring can be a reason for this warning light 
  • Damage fuel vapor hoses
  • Blown fuses are a sign of some serious problems 
  • Failed PCM
  • Faulty pressure sensor 

Diagnosis Of P0499 obd2 Code

Once the detector has diagnosed the code P0499, now is the time to diagnose the possible and root cause of this fault code. First of all, you must check all the wires, connectors and look at all the other electrical parts of the emission system.

  • First of all, you must inspect the gas cap to check if it is loose. If the cap is loose, then you must tight it as this way you can clear the code. You must also check the gas cap for the damage. Though it is a bit difficult to detect. 
  • Do not forget to check disconnected or cracked fuel vapor hoses and if you find any damage there, clear that to cleat the P0699 code.
  • Inspect the charcoal canister and look if there is any leakage or damage. Replace the charcoal canister as soon as possible. 
  • Inspect the canister vent valve to test the power, and resolve the issue if you find anyone. 
  • If all of these steps do not work for you, take the help of a professional!

And, as you find out the root cause of the damage, repair the damage. After resolving the issue from Powertrain Control Module, you can also restore the system. 

In addition, do not forget to check if there is any issue with the EVAP emission system if the error code reappears on your screen. 

Tools You Need To Diagnose P0499 Code

In order to diagnose the code p0499, you need a digital multimeter. The tool is used to measure the voltage, resistance, or current. The recorded values appear on the screen/display. Therefore, even first-time users can also read the values. 

Mistakes You Should Avoid While Diagnosing the Code P0499 

There are multiple mistakes that a person can make while diagnosing the code po499. For instance, most people try to replace the EVAp emissions system components. well, that is a good decision, but it would be better if check the vacuum leak or vacuum pump.

In addition, you must also check if you have not installed a fuel cap properly. The chances of errors in these parts are pretty higher as compared to other parts. Therefore, it is far better to check them before you inspect or change any other part. 

How to fix the P0499 obd2 Code?

How to fix P0499 Code?

To fix this problem, you must follow the under given steps:

  1. Properly install the improperly installed fuel cap 
  2. Replace the broken or damaged charcoal canister 
  3. Change the faulty pressure sensor 
  4. You should also replace the blown fuses 
  5. Replace the fuel vapor hoses if they are damaged or cracked 
  6. Change the faulty purge control solenoid
  7. Check if the EVAp canister valve is damaged and if it is don’t take much time to replace it

Tips to Avoid P0499 Code in Future

The common misdiagnosis can make the situation worst. Therefore, it is pretty important to diagnose the issue properly and then take the necessary actions to resolve the problem as early as possible. After every change you make in the system or repair do not forget to clear the code. 

If the code P0499 does not appear again, it means the last repair you made has resolved the issue. So, this way you can easily resolve the issue and it also keeps you from any problems in the future. 


The abnormal pressure in the emission system is the major cause of this issue. Once you have successfully detected the exact reason for the p0499 code, it will be easy and quick to resolve the problem. 

Plus, you can also keep all the expected reasons in mind which can help you in the future if you face this type of issue.