Understanding the P0420 Code on Your 2020 Dodge Charger
A P0420 code on your 2020 Dodge Charger means the powertrain control module (PCM) has detected that the Bank 1 catalytic converter isn't converting exhaust gases efficiently enough. The 2020 Charger is available with several engine options including the 3.6L Pentastar V6 (292 hp), the 5.7L HEMI V8 (370 hp), the 6.4L HEMI V8 (485 hp in the Scat Pack), and the supercharged 6.2L HEMI in the Hellcat. Since P0420 specifically references Bank 1, this is most relevant on the V6 and V8 configurations where Bank 1 is the side of the engine with cylinder number one.
Before you panic about needing a new catalytic converter, there are several possible causes that are worth investigating. Let's break it all down.
Symptoms You May Experience
- Illuminated check engine light — Often the only noticeable symptom
- Decreased fuel efficiency — You may see a drop of 1-3 MPG
- Sulfur smell from the exhaust — A rotten egg odor indicates converter issues
- Slight power reduction — Some drivers report a subtle loss of responsiveness
- Emissions test failure — This code guarantees a failed inspection in testing states
Most Common Causes of P0420 in the 2020 Charger
1. Worn Catalytic Converter
With the 2020 model now having several years of service, the catalytic converter may be wearing out, especially on higher-mileage Chargers. The HEMI V8 engines produce more exhaust heat which can accelerate converter degradation. The internal catalyst substrate breaks down over time, reducing its ability to process exhaust gases.
2. Downstream Oxygen Sensor Failure
The post-catalytic converter O2 sensor on Bank 1 monitors converter performance. A sluggish or inaccurate sensor can trigger a false P0420. On the Charger's V6 and V8 engines, the Bank 1 downstream sensor is accessible from underneath the vehicle.
3. Exhaust System Leaks
Leaks in the exhaust manifold, gaskets, or piping between the engine and the downstream sensor can introduce oxygen into the exhaust stream. This throws off the O2 sensor readings and can trigger the P0420 code. The Charger's exhaust manifold bolts are known to occasionally loosen over time.
4. Engine Misfires or Rich Running Condition
Consistent misfires dump unburned fuel into the catalytic converter, which can overheat and damage the catalyst material. If your Charger has had misfire codes in the past that were ignored, the converter may have been damaged as a result.
Diagnostic Steps
- Pull all stored codes — Look for companion codes like P0430 (Bank 2), misfire codes, or O2 sensor codes that provide additional clues.
- Monitor live O2 sensor data — Compare the upstream and downstream O2 sensor signals. A healthy converter shows a relatively flat downstream signal while the upstream fluctuates.
- Perform a visual exhaust inspection — Check for leaks, rust, physical damage, or loose heat shields around the catalytic converter area.
- Temperature test — Using an infrared thermometer, the outlet of the catalytic converter should be hotter than the inlet. If it's cooler, the converter isn't working properly.
Repair Options and Costs
- Catalytic converter replacement: $1,000 – $2,500 depending on engine type. HEMI V8 converters are more expensive than V6 units.
- Downstream O2 sensor replacement: $120 – $300 including labor. A relatively quick and affordable fix.
- Exhaust leak repair: $100 – $450 depending on location. Manifold gaskets and flange repairs are common.
- Engine misfire repair: $150 – $600 covering spark plugs, coils, or injectors as needed.
Is It Safe to Drive?
A P0420 code on its own is not a safety hazard. Your 2020 Charger will continue to run and drive normally in most cases. However, prolonged driving with a failing converter can eventually lead to restricted exhaust flow, which could cause overheating and reduced engine performance. Get it checked within a few weeks.
Prevention Tips
- Address misfire codes immediately — Misfires are the number one killer of catalytic converters
- Use quality fuel — Especially important for the HEMI engines
- Keep up with oil changes — Oil burning leads to converter contamination
- Don't ignore other check engine lights — Small problems can cascade into converter damage