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Error Code P0468 is defined as EVAP Control System Malfunction or Purge Flow Sensor High Input. It can appear together with related Error Codes P0440 or P0442, which often indicates loose gas cap, or P0443 up to P0449, which means a problem in the EVAP Purge Valve.
This code is a generic trouble code, meaning it applies to all vehicles equipped with OBD-II, especially those made from 1996 up to the present day. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another.
Error Code P0468 means that the EVAP Control System is malfunctioning, which is often caused by an open circuit between the purge flow sensor and the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes). It may also be caused by other affected components, such as issues in the gas cap, fuel lines, purge valve, pressure and flow sensors, connectors, hoses, wiring, vacuum lines or fuel tank.
As with other error codes, this code activates the Check Engine light and registers the code to the vehicle’s memory system. There are usually no other drivability or performance issues that accompany this code. However, in many cases, there are other stored codes related to the evaporative emission control system, which may come with their own set of symptoms.
There many problems that lead to this code, such as:
- Clogged or damaged charcoal canister
- Faulty purge control solenoid
- Broken or cracked fuel vapor
- Broken or cracked vacuum hoses
- Malfunctioning pressure or flow sensor
- Improperly installed gas cap
- PCM failure (rare)
How to Check
To diagnose this code, technicians use combination methods, which require the use of a scanner, voltmeter, and a smoke machine (to detect leaks). The inspection usually starts with a visual inspection of the EVAP Emission Control System wiring and connectors to look for corroded, disconnected, or damaged parts. Damaged parts must be replaced.
After replacing the damaged parts, the technician will proceed with their diagnosis by retesting the system and connecting the scanner to record the freeze frame data and stored codes.
Next, they set clear all the codes and then take the vehicle for a test drive to see if the code comes back. If there is a leak present and the gas cap is installed securely, they will proceed on inspecting vacuum and fuel vapor hoses and look for signs of breaks and kinks. Any damages must be repaired, if not replaced. If the hoses are in good condition, the mechanic will check for corrosion or damage to the purge valve and charcoal canister.
If none of these actions results in a solution, technicians usually proceed on using a smoke machine to pinpoint the location of the leak.
How to Fix
Common repairs for this code include:
- Replacement of Purge Flow sensor
- Proper installation of the fuel cap
- Repair or replacement of connectors, wiring, hoses, charcoal canister or Purge Control Solenoid
Though this code doesn’t usually cause drivability and performance problems for the vehicle, it is important to get it fixed as soon as possible to avoid affecting other components of the EVAP Emission Control System.