P0420 Catalyst System Efficiency Below Threshold Bank 1
Most common: The catalytic converter is in need of replacement.
Possible causes
– Three way catalyst converter Bank 1
– Exhaust tube
– Intake air leaks
– Fuel injectors may be faulty
– Fuel injector leaks
– Spark plugs may be faulty
– Improper ignition timing
– Engine Control Module (ECM)
Tech notes
The most common cause it the three way catalyst converter Bank 1. Changing just the O2 sensor usually don’t repair the problem. If the P0420 code is combined with other codes, try fixing the other codes first.
When is the code detected?
– Three way catalytic converter Bank 1 does not operate properly.
– Three way catalyst converter Bank 1 does not have enough oxygen storage capacity.
P0420 Description
The Engine Control Module (ECM) monitors the switching frequency ratio of heated oxygen sensors 1 (front O2 sensor) and heated oxygen sensors 2 (rear O2 sensor).
A three way catalyst converter (Manifold) with high oxygen storage capacity will indicate a low switching frequency of heated oxygen sensor 2. As oxygen storage capacity decreases, the heated oxygen sensor 2 switching frequency will increase.
When the frequency ratio of heated oxygen sensors 1 and 2 approaches a specified limit value, the three way catalyst malfunction is diagnosed.
P0441 Evaporative Emission Control System Incorrect Purge Flow
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
– Possible a noticeable fuel odor caused by the release of fuel vapors
Possible causes
– Missing Fuel cap
– Incorrect fuel filler cap used
– Fuel filler cap remains open or fails to close
– Foreign matter caught in fuel filler cap
– Incorrect fuel tank vacuum relief valve
Tech notes
Loose or damage fuel tank filler cap may trigger the P0441 code.
When is the code detected?
– Pressure in charcoal canister and fuel tank does not drop during purge control (2 trip detection logic)
– During purge cut off, negative pressure incoming in the charcoal canister and fuel tank will not stop. (2 trip detection logic)
P0441 Description
The vapor pressure sensor, Voltage Solenoide Valve (VSV) for EVAP, Voltage Solenoide Valve (VSV) for canister closed valve (CCV) and Valve Solenoide Valve (VSV) for pressure switching valve are used to detect abnormalities in the evaporative emission control system.
The ECM decides whether there is an abnormality in the evaporative emission control system based on the vapor pressure sensor signal.
Diagnostic Trouble Code (DTC) P0441 is recorded by the ECM when there is a malfunction in either the VSV for EVAP, the VSV for pressure switching valve, or in the vapor pressure sensor itself, or when evaporative emissions leak from the components within the dotted line in Fig. 1 below.
The ECM closes the CCV and opens the VSV for pressure switching valve causing vacuum to increase in the entire EVAP system.
The ECM continues to operate the VSV for EVAP until the vacuum is increased to a specified point at which time the ECM closes the VSV for EVAP.
If the vacuum did not increase, or if the vacuum increased beyond the specified limit, the ECM judges the VSV for EVAP and related components to be faulty.
P0442 EVAP Control System Leak Detected Small Leak
This diagnosis detects leaks in the EVAP purge line using engine intake manifold vacuum. If pressure does not increase, the Engine Control Module (ECM) will check for leaks in the line between the fuel tank and EVAP canister purge volume control solenoid valve under the following vacuum test condition.
The vacuum cut valve bypass valve is opened to clear the line between the fuel tank and the EVAP canister purge volume control solenoid valve. The EVAP canister vent control valve will then be closed to shut the EVAP purge line off. The EVAP canister purge volume control solenoid valve is opened to depressurize the EVAP purge line using intake manifold vacuum. After this depressurization is implemented, the EVAP canister purge volume control solenoid valve will be closed.
P0420 Catalyst System Efficiency Below Threshold Bank 1
Most common: The catalytic converter is in need of replacement.
Possible causes
– Three way catalyst converter Bank 1
– Exhaust tube
– Intake air leaks
– Fuel injectors may be faulty
– Fuel injector leaks
– Spark plugs may be faulty
– Improper ignition timing
– Engine Control Module (ECM)
Tech notes
The most common cause it the three way catalyst converter Bank 1. Changing just the O2 sensor usually don’t repair the problem. If the P0420 code is combined with other codes, try fixing the other codes first.
When is the code detected?
– Three way catalytic converter Bank 1 does not operate properly.
– Three way catalyst converter Bank 1 does not have enough oxygen storage capacity.
P0420 Description
The Engine Control Module (ECM) monitors the switching frequency ratio of heated oxygen sensors 1 (front O2 sensor) and heated oxygen sensors 2 (rear O2 sensor).
A three way catalyst converter (Manifold) with high oxygen storage capacity will indicate a low switching frequency of heated oxygen sensor 2. As oxygen storage capacity decreases, the heated oxygen sensor 2 switching frequency will increase.
When the frequency ratio of heated oxygen sensors 1 and 2 approaches a specified limit value, the three way catalyst malfunction is diagnosed.
P0441 Evaporative Emission Control System Incorrect Purge Flow
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
– Possible a noticeable fuel odor caused by the release of fuel vapors
Possible causes
– Missing Fuel cap
– Incorrect fuel filler cap used
– Fuel filler cap remains open or fails to close
– Foreign matter caught in fuel filler cap
– Incorrect fuel tank vacuum relief valve
Tech notes
Loose or damage fuel tank filler cap may trigger the P0441 code.
When is the code detected?
– Pressure in charcoal canister and fuel tank does not drop during purge control (2 trip detection logic)
– During purge cut off, negative pressure incoming in the charcoal canister and fuel tank will not stop. (2 trip detection logic)
P0441 Description
The vapor pressure sensor, Voltage Solenoide Valve (VSV) for EVAP, Voltage Solenoide Valve (VSV) for canister closed valve (CCV) and Valve Solenoide Valve (VSV) for pressure switching valve are used to detect abnormalities in the evaporative emission control system.
The ECM decides whether there is an abnormality in the evaporative emission control system based on the vapor pressure sensor signal.
Diagnostic Trouble Code (DTC) P0441 is recorded by the ECM when there is a malfunction in either the VSV for EVAP, the VSV for pressure switching valve, or in the vapor pressure sensor itself, or when evaporative emissions leak from the components within the dotted line in Fig. 1 below.
The ECM closes the CCV and opens the VSV for pressure switching valve causing vacuum to increase in the entire EVAP system.
The ECM continues to operate the VSV for EVAP until the vacuum is increased to a specified point at which time the ECM closes the VSV for EVAP.
If the vacuum did not increase, or if the vacuum increased beyond the specified limit, the ECM judges the VSV for EVAP and related components to be faulty.
P0442 EVAP Control System Leak Detected Small Leak
This diagnosis detects leaks in the EVAP purge line using engine intake manifold vacuum. If pressure does not increase, the Engine Control Module (ECM) will check for leaks in the line between the fuel tank and EVAP canister purge volume control solenoid valve under the following vacuum test condition.
The vacuum cut valve bypass valve is opened to clear the line between the fuel tank and the EVAP canister purge volume control solenoid valve. The EVAP canister vent control valve will then be closed to shut the EVAP purge line off. The EVAP canister purge volume control solenoid valve is opened to depressurize the EVAP purge line using intake manifold vacuum. After this depressurization is implemented, the EVAP canister purge volume control solenoid valve will be closed.
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