P0497 OBD-II Trouble Code: Evaporative Control System Malfunction
Diagnostic Trouble Code (DTC): P0497
P0497 code definition
The P0497 code, or Evaporative Emission System Low Purge Flow, is indicative of a problem somewhere in the EVAP control system.
What the P0497 code means
When a vehicle sets the P0497 code, it lets you know that there is a fault in the evaporative control system, the system which helps to regulate the amount of fuel vapor that is released into the environment. As the engine runs and fuel is burned, a canister in the EVAP control system stores the excess fuel vapors coming from the gas tank.
The pressure that is built up through this process is vented through a vent line and EVAP vent solenoid, and the vapors are stored in the canister until the engine uses them up. If there is a leak or other fault in the system, the pressure of these products is affected, and the PCM (powertrain control module) will detect a difference in the pressure level. Code P0497 is detected when there is a change in the way this pressure normally flows.
What causes the P0497 code?
There are several components in the EVAP control system which could trigger a vehicle to throw this code, including:
- An ill-fitting gas cap
- A short in the EVAP canister vent valve wiring harness
- A clogged EVAP charcoal canister
- A faulty EVAP canister vent valve
- A compromised connection in the canister vent valve circuit
- A faulty pressure sensor
- Damaged or disconnected vacuum or fuel vapor hoses
What are the symptoms of the P0497 code?
There may not be any discernible symptoms with this code, beyond an illuminated Check Engine light. However, any EVAP malfunction can affect fuel economy as well as emissions released by the vehicle, which could cause you to fail an emissions test.
How does a mechanic diagnose the P0497 code?
Procedures required to pinpoint an EVAP purge flow problem may include:
- Recording stored codes and freeze frame data with a scanner, and clearing those codes from the vehicle’s memory to see if they return
- Visual inspection of the charcoal canister, purge valve, hoses, wiring, and connections
- Starting the engine and listening for vacuum leaks at the purge control valve and hose
- Using a smoke machine to reveal leaks among the network of hoses that make up the EVAP system
- Performing a resistance check on the purge control solenoid and surrounding components
Common mistakes when diagnosing the P0497 code
Because the gas cap is such a simple fix in EVAP purge flow problems, it is often overlooked as a culprit in this code. Checking each possibility, no matter how minor, can help prevent unnecessary and costly repairs.
How serious is the P0497 code?
While the vehicle will typically run with this code, it can cause a drop in fuel efficiency and an increase in emissions released into the atmosphere. It’s best to have the issue addressed as soon as possible.
What repairs can fix the P0497 code?
Repair procedures for this code depend upon what is found by the diagnostic process, and may include:
- Reconnection of hoses or loose connectors
- Wiring replacement
- Charcoal canister replacement
- Canister purge valve replacement
- Gas cap replacement
- Clearing of codes and retesting with a scanner to ensure the problem is fixed
Additional comments for consideration regarding the P0497 code
Even if hoses aren’t damaged or disconnected, they may become kinked, so your technician should check for this issue. When performing a smoke machine test on the system to check for leaks, it is normal for a low flow of smoke to escape the vent in the charcoal canister. Flow codes are often most efficiently diagnosed by beginning inspection at the canister and the surrounding components.
Need help with a P0497 code?
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