P0420 on Chrysler
Catalyst System Efficiency Below Threshold (Bank 1)
P0420 on Chrysler vehicles indicates catalyst system efficiency below threshold (bank 1). Au7o has documented this code across 2 Chrysler models — most commonly on 200, 300. P0420 means the engine computer determined the catalytic converter on Bank 1 isn't cleaning the exhaust as efficiently as it should. The computer compares the upstream and downstream oxygen sensors; a healthy converter stores and releases oxygen, so the downstream sensor should read fairly steady, while a worn one lets its readings mirror the upstream sensor. When that efficiency falls below a set threshold, this code is set. While it most often points to a worn-out catalytic converter, it can also be triggered by upstream problems like a faulty oxygen sensor or an exhaust leak, so the converter isn't always the actual fault. Typical repair costs on Chrysler range from $400 to $8,500, depending on the specific model and root cause.
Common Causes of P0420
- •Worn-out or failing catalytic converter (Bank 1)
- •Faulty or aged downstream (or upstream) oxygen sensor
- •Exhaust leak before or near the oxygen sensors
- •Engine running rich or lean (fuel trim issues)
- •Misfires or oil/coolant contaminating the converter
- •Damaged or aftermarket low-quality catalytic converter
- •Faulty oxygen sensor wiring or connectors
- •Software/calibration needing update (on some vehicles)
P0420 on Chrysler by Model
Chrysler 200(1 issue)
- 2.4L Tigershark Excessive Oil Consumption2015-2017
The 2.4L Tigershark MultiAir II engine has defective piston rings that allow oil into the combustion chamber. Owners report consuming 1 quart of oil every 500-1,000 miles. Engine can seize without warning if oil drops too low. Class-action settlement (Wood, et al. v. FCA US, LLC) reached. FCA extended powertrain warranty to 7 years/100,000 miles under CSN W80.
Chrysler 300(1 issue)
- 5.7L HEMI Exhaust Manifold Bolt Failure2005-2023
The 5.7L HEMI is notorious for exhaust manifold bolts breaking, especially on the passenger side. Thermal cycling causes bolts to become brittle and snap. Creates a ticking noise at cold startup that partially diminishes as engine warms but never fully goes away. Broken bolts can be extremely difficult to extract if snapped flush with the cylinder head.
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View P0420 across all makes →Frequently Asked Questions
What does P0420 mean on Chrysler?▼
P0420 stands for "Catalyst System Efficiency Below Threshold (Bank 1)." P0420 means the engine computer determined the catalytic converter on Bank 1 isn't cleaning the exhaust as efficiently as it should. The computer compares the upstream and downstream oxygen sensors; a healthy converter stores and releases oxygen, so the downstream sensor should read fairly steady, while a worn one lets its readings mirror the upstream sensor. When that efficiency falls below a set threshold, this code is set. While it most often points to a worn-out catalytic converter, it can also be triggered by upstream problems like a faulty oxygen sensor or an exhaust leak, so the converter isn't always the actual fault. On Chrysler specifically, this code is documented across 2 models.
What causes P0420 on Chrysler vehicles?▼
Common causes on Chrysler: Worn-out or failing catalytic converter (Bank 1), Faulty or aged downstream (or upstream) oxygen sensor, Exhaust leak before or near the oxygen sensors, Engine running rich or lean (fuel trim issues), Misfires or oil/coolant contaminating the converter. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0420 on a Chrysler?▼
Repair costs on Chrysler range from $400 to $8,500, depending on the specific model and root cause.
Which Chrysler models have P0420 documented?▼
Au7o has documented P0420 on 2 Chrysler models: 200, 300.