Modifying your 2016 Hellcat for enhanced performance is a thrilling endeavor. Upgrading components like headers and catalytic converters can significantly boost horsepower and engine sound. However, these modifications often trigger OBD2 codes, particularly related to your oxygen (O2) sensors and catalytic converter efficiency. Understanding and addressing these codes is crucial to ensure your Hellcat runs smoothly and avoids issues. This article will guide you through diagnosing and resolving common OBD2 code problems after performance modifications on your 2016 Hellcat.
Understanding O2 Sensor Codes After Header Installation
Installing aftermarket headers on your Hellcat can alter the exhaust flow and affect your O2 sensors, often leading to codes. One key adjustment to consider is the O2 transport delay. Experienced tuners recommend increasing the O2 transport delay tables by approximately 150% after header installation. This adjustment helps the ECU properly interpret the sensor readings in the modified exhaust system. While it might be tempting to simply disable O2 sensor codes like P0133 or P0153, this is not advisable as it can render your O2 sensors unsupported for emissions monitoring. You can, however, uncheck the “MIL” (Malfunction Indicator Lamp) box for these codes in your tuning software to prevent the check engine light from illuminating on your dashboard, but the code will still be registered.
Alt text: Close-up of a car’s undercarriage showcasing the catalytic converter and oxygen sensor, key components in emission control and OBD2 system monitoring.
Dealing with Catalytic Converter Efficiency Codes with High Flow Cats
Upgrading to high-flow catalytic converters aims to improve exhaust flow, but it can also impact your downstream O2 sensor readings and trigger efficiency codes like P0420 (Catalyst System Efficiency Below Threshold Bank 1) and P0430 (Catalyst System Efficiency Below Threshold Bank 2). On a vehicle with factory catalytic converters, downstream O2 sensors at idle typically read in the 0.650-0.710 voltage range for each bank. In contrast, high-flow cats often result in readings in the 0.020-0.060 range. This difference occurs because factory cats are more restrictive and facilitate secondary combustion more efficiently within the converter, leading to higher voltage readings. High-flow cats, while beneficial for performance, are less restrictive.
To address this, especially to pass emissions tests, O2 sensor defoulers are a common solution. These spacers reposition the downstream O2 sensor out of the direct exhaust stream. To use them effectively, you may need to slightly modify the defouler by drilling the hole with a 7/16 inch drill bit to accommodate the Dodge O2 sensor without causing damage. For added effectiveness in reducing emissions readings, consider inserting a small piece of steel wool from a kitchen cleaning pad into the defouler before installing the O2 sensor. Pack it in to ensure it stays in place. Apply this defouling method to both downstream O2 sensors to maintain balanced fuel trims.
Alt text: Diagram showing the installation of an O2 sensor defouler on a car’s exhaust pipe, illustrating how it spaces out the sensor to modify readings.
While defouling addresses the sensor readings, you can also consider ECU tuning adjustments. It is generally safe to disable the P0430 code entirely in your tune without causing issues with catalyst support monitoring. However, disabling P0420 is not recommended as it can lead to the catalyst test becoming unsupported for Bank 1. Remember to only disable P0430 and leave P0420 enabled to ensure proper system monitoring.
Addressing O2 Slow Response Codes
If you encounter O2 slow response codes, particularly after modifications or on older vehicles, first inspect your upstream O2 sensors for any physical damage. It’s critical to emphasize that you should never cut and solder an O2 sensor cable. If you encounter a damaged cable, discard the sensor and replace it. Use O2 sensor extenders if necessary to ensure proper fitment of a new sensor, especially if you’ve changed exhaust components. Also, handle O2 sensors with care, as dropping them can damage the internal heater element.
Bonus Tip – EVAP System Codes
For a quicker emissions readiness test, you can try disabling codes P0456 (Evap System Small Leak) and P0457 (Evap System Large Leak) specifically within the EVAP system settings of your tune. This trick can sometimes help the EVAP system test complete instantly on many vehicles, though results can vary, as noted with a 2019 Charger Scat Pack where this may not work. Experiment to see if this works for your Hellcat.
Passing Emissions Tests
To ensure your 2016 Hellcat passes the catalytic converter test during an emissions inspection, follow these drive cycle steps: drive at a steady speed of 38 mph between 1350-1850 rpm, typically in 4th gear, for approximately 2 minutes. If the test is interrupted, simply resume the same driving conditions when it is safe to do so. Alternatively, you can cruise at 55 mph for 8 minutes, then come to a complete stop and let the engine idle for 3 minutes before turning it off. Turn the key back to the “on” position, and the catalytic converter test, along with other readiness tests, should be complete.
Persistent Issues? Double Defoul Bank 1.
If you continue to experience OBD2 code issues after implementing these solutions, and you are confident that your engine is running well mechanically, consider using a double defouler setup on Bank 1 as a last resort. This involves stacking two defoulers to further reduce the downstream O2 sensor’s exposure to the exhaust stream on the affected bank. Ensure you have sufficient space for this configuration.
By following these steps, you should be well-equipped to troubleshoot and resolve OBD2 code issues on your 2016 Hellcat after performance modifications, keeping your car running optimally and emissions-compliant.
