A prevalent issue with the Toyota Land Cruiser is the P0446 code. This code corresponds to a specific number obtained when connecting your Land Cruiser to an OBDII scanner.
A faulty vent control valve most commonly causes P0446.
Definition | P0446: EVAP System – Vent Control Circuit – Malfunction |
Symptoms | Usually none |
Common Causes | Bad EVAP Vent Control Valve |
Breakdown Risk? | No |
Repair Cost (Parts) | Under $100 for most common parts |
Repair Difficulty | Moderate |
Table of Contents
P0446 is a standard OBDII trouble code, applicable to any make or model of vehicle, whether it’s a Land Cruiser or not.
Here’s its technical definition:
P0446: Evaporative Emission Control System → Vent Control Circuit → Malfunction
In layman’s terms, P0446 indicates a problem with the EVAP system vent control valve.
It often appears with other error codes, such as P0420, P0441, or P0440.
The definition encompasses three components: first, the extensive system impacted by the code; second, the specific segment; and third, the nature of the error.
The EVAP system captures all fuel vapor from the fuel tank and sends them to the engine’s intake manifold to be ignited in the normal combustion process.
When the EVAP vent control valve regulates and helps maintain pressure in the Toyota Land Cruiser’s fuel tank.
It is usually closed during regular operation, which helps prevent any fuel vapors from escaping into the atmosphere.
The P0446 trouble code will appear when the vent control valve is not responding to prompts to open and close from the PCM (Powertrain Control Module).
Typically, the only symptom of P0446 will be the check engine light.
The only other symptoms of P0446 in the Toyota Land Cruiser are a slight decrease in fuel economy. However, P0446 may also cause a gas smell.
There are many things that can cause the P0446 trouble code to trigger in your Toyota Land Cruiser.
Here are the most common problems that will throw the code:
The most common causes of P0446 are:
It can be tough to diagnose P0446 at home.
A mechanic has many instruments at his disposal to diagnose what would be causing the P0446 in your Toyota Land Cruiser.
Here are the most common things that are done to diagnose the code:
The fuel tank pressure will be checked and monitored. If you’re at home trying to diagnose P0446, you can use a little anecdotal evidence to determine if the vent control valve is stuck shut or not.
Do you notice a loud hissing when you take off the fuel cap? If so, that indicates that the vent control valve is stuck shut.
It’s important to note that the exact order of diagnosis may vary depending on your Land Cruiser’s model year and engine/transmission options.
Here are the most common Land Cruiser P0446 fixes:
Of all the items listed above, it would be wise to start with the gas cap and work your way to the fuel tank since the gas cap is far and away the easiest and least expensive item to replace on the list.
It is safe to drive your Land Cruiser with error code P0446. The vent control valve does not affect how your vehicle’s engine runs.
However, like any OBD II code, you shouldn’t ignore the problem and repair your Land Cruiser as soon as possible.
The vent control valve can be anywhere close to the charcoal canister, depending on the model year and options chosen when built.
It’s easy to find. There will be a tube going from the gas tank to the charcoal canister. The charcoal canister will have two tubes exiting it One tube leading to the engine and one going back to the gas tank. The vent control valve will be next to these tubes on the charcoal canister.
The fuel tank is the most expensive item you would have to replace to repair error code P0446. But, it’s rarely the cause of P0446 in the Toyota Land Cruiser.
P0446 is a diagnostic trouble code (DTC) associated with a vehicle’s evaporative emissions control system.
It signifies an issue in the vent control circuit in your Toyota Land Cruiser’s EVAP system, which prevents fuel vapor from being released into the atmosphere.
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