P0420 - Catalyst System Efficiency Below Threshold (Bank 1)

Powertrain DTC Charts and Descriptions 4-67

Diagnostic Trouble Code (DTC) Charts and Descriptions

P0420 - Catalyst System Efficiency Below Threshold (Bank 1)

Description: This DTC sets when the bank 1 catalyst system efficiency is below the acceptable threshold.

Possible Causes: • Damaged heated oxygen sensor (HO2S)

• Exhaust leaks

• Damaged exhaust manifold

• Damaged catalytic converter

• Oil contamination

• Cylinder misfiring

• Downstream HO2S wires incorrectly connected

• Damaged exhaust system pipe

• Damaged muffler and tailpipe assembly

• Evaporative emission (EVAP) purge valve stuck open

• Leaking fuel injector

Diagnostic Aids: Under normal closed loop fuel conditions, high efficiency catalysts have oxygen storage which reduces the

frequency and amplitude of the downstream HO2S. As catalyst efficiency deteriorates, its ability to store oxygen declines and the downstream HO2S signal has an increased amplitude and frequency. The PCM compares the signal line length of the downstream HO2S to an expected signal line length of the downstream HO2S with a deteriorated catalytic converter.

Application Key On Engine Off Key On Engine Running Continuous Memory

All GO to Pinpoint Test HF.

P0430 - Catalyst System Efficiency Below Threshold (Bank 2)

Description: This DTC sets when the bank 2 catalyst system efficiency is below the acceptable threshold.

Possible Causes: • Damaged heated oxygen sensor (HO2S)

• Exhaust leaks

• Damaged exhaust manifold

• Damaged catalytic converter

• Oil contamination

• Cylinder misfiring

• Downstream HO2S wires incorrectly connected

• Damaged exhaust system pipe

• Damaged muffler and tailpipe assembly

• Evaporative emission (EVAP) purge valve stuck open

• Leaking fuel injector

Diagnostic Aids: Under normal closed loop fuel conditions, high efficiency catalysts have oxygen storage which reduces the

frequency and amplitude of the downstream HO2S. As catalyst efficiency deteriorates, its ability to store oxygen declines and the downstream HO2S signal has an increased amplitude and frequency. The PCM compares the signal line length of the downstream HO2S to an expected signal line length of the downstream HO2S with a deteriorated catalytic converter.

Application Key On Engine Off Key On Engine Running Continuous Memory

All GO to Pinpoint Test HF.

P0442 - Evaporative Emission System Leak Detected (Small Leak)

Description: This DTC sets when a fuel vapor leak from an opening as small as 1.016 mm (0.040 in) is detected by the

EVAP running loss monitor test.

Possible Causes: • Aftermarket EVAP hardware that does not conform to the required specifications

• Small holes or cuts in the fuel vapor hoses or tubes

• EVAP canister vent valve stays partially open on closed command

• Damaged, missing or loosely installed fuel filler cap (if equipped)

• Capless fuel tank filler pipe damaged or not sealed correctly (if equipped)

• Loose fuel vapor hose or tube connections to the EVAP system components

• EVAP system component seals leaking at or near the EVAP purge valve, fuel tank pressure (FTP) sensor,

EVAP canister vent valve, fuel vapor control valve tube assembly or fuel vapor vent valve assembly

Diagnostic Aids: Check for a missing fuel filler cap or the integrity of the cap (if equipped).

Verify the capless fuel tank filler pipe is sealed correctly (if equipped). Install and remove the supplemental fueling adapter five times in the capless fuel tank filler pipe to clear debris on the seal. Refer to the Owner Literature for the location of the supplemental fueling adapter in the vehicle. Check for loose or damaged vapor hoses. Visually inspect the EVAP canister inlet port, EVAP canister vent valve filter, and canister vent hose assembly for contamination or debris.

Application Key On Engine Off Key On Engine Running Continuous Memory

2016 Powertrain Control/Emissions Diagnosis, Gasoline Engines, 3/2015