Error Code P0497 is defined as Evaporative Control System Malfunction, which is an indication of a problem somewhere in EVAP control system. This is a generic trouble code, meaning it applies to all vehicles equipped with the OBD-II system, or vehicles made in 1996 up to present. It is particularly common among Ford, Honda, Mazda, Mercedes Benz and Volkswagen vehicles, though it can also appear in other brands. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another.

The EVAP system uses a closed reservoir to capture fuel vapors to keep them from escaping into the atmosphere and store excessive vapors until the engine is ready to burn them. With this, fuel vapors are routed to the reservoir (canister) using a specially designed valve and a network of metal tubes and rubber hoses. The pressure that is built when the fuel is stored causes the vapors to vent into the tubes, and eventually lead to the canister. This canister contains a charcoal element which absorbs fuel vapors, which will be released at the right time.

The purge control solenoid is activated by the vehicle’s computer, or PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) reads it that the engine is ready to burn the EVAP fuel vapors efficiently. To monitor the efficiency of the EVAP system, and EVAP pressure sensor is included in the system.

When this code is set, that means the PCM has detected a low flow condition in the EVAP (evaporative emission) purge system. This means there’s a fault in the EVAP control system, which could be a leak or other faults in the system. Due to the change in how the pressure flows, Error Code P0497 will be detected by the PCM.

Common Symptoms

As with other error codes, this code activates the Check Engine light and registers the code to the vehicle’s memory system. Other symptoms may include:

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  • Increase in fuel consumption
  • Poor engine idle quality
  • Leaking sound coming from the underhood area

In most cases, however, this code may not show any symptoms at all.

Possible Causes

The EVAP system is composed of multiple parts, which is why this code can be caused by many different problems, such as:

  • Short in the EVAP canister vent valve harness
  • Clogged EVAP charcoal canister
  • Cracked, crimped, or collapsed vacuum hoses or lines
  • Defective EVAP canister vent valve
  • Ill-fitting gas cap
  • Fault in the canister vent valve circuit connection
  • Defective pressure sensor
  • Disconnected or damaged vacuum or fuel vapor hoses

How to Check

Diagnosis of this code starts with the use of OBD scanner to scan and record the freeze frame data of the code. The codes are then cleared from the vehicle’s memory to check if they return.

Next, technicians proceed on conducting a visual inspection of the charcoal canister, hoses, purge valve, wiring, and all related connections.

Then, the technician will start the engine to be able to listen to the vacuum leaks at the purge control valve and hose.

Technicians will usually proceed on using a smoke machine to detect any possible leaks in the hoses the make up the EVAP system.

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Lastly, they perform a resistance check on the purge control solenoid and its surrounding components.

How to Fix

Common repair procedures for this code include:

  • Reconnection of loose connectors or hoses
  • Repair or replacement of wiring
  • Vacuum replacement
  • Replacement of charcoal canister
  • Replacement of canister purge valve
  • Replacement of gas cap

The gas cap is the easiest fix for this code; however, it is also the most overlooked. To prevent making unnecessary replacements, make sure you check the gas cap first.