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2017 CR-V Check Engine Light - P0420 Code

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Sarah K. · rep 0 · May 25, 1:45 AM · 1 replies · solved · Question

Vehicle: 2017 Honda CR-V EX-L

Hey everyone,

My 2017 Honda CR-V EX-L, with about 85,000 miles, just threw a check engine light. I scanned it with my OBD-II reader, and it's showing a P0420 code: 'Catalyst System Efficiency Below Threshold (Bank 1)'.

The car seems to be driving fine, no noticeable loss of power or strange noises. Fuel economy also seems normal. I've heard this code can sometimes be a false alarm or related to O2 sensors, not necessarily the catalytic converter itself.

Has anyone else experienced this with their CR-V? What steps did you take? Should I try clearing the code and seeing if it comes back, or is it better to get it looked at right away? Any advice would be greatly appreciated!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 1:45 AM

0

ClearTheCode admin answer:

The P0420 code on your 2017 Honda CR-V indicates that the catalytic converter's efficiency is below the required threshold. While it might not always mean a faulty catalytic converter, it's a common issue that needs attention.

Here are the common causes and steps to diagnose:

  1. Oxygen Sensors: A failing upstream or downstream oxygen sensor can send incorrect readings to the engine control unit (ECU), triggering a P0420. The downstream sensor is particularly critical for monitoring converter efficiency.
  2. Exhaust Leaks: Leaks in the exhaust system before or near the catalytic converter can allow unmetered air in, affecting O2 sensor readings and leading to a false P0420.
  3. Engine Misfires or Rich/Lean Conditions: Persistent engine misfires, running too rich (too much fuel), or too lean (not enough fuel) can damage the catalytic converter over time by overheating it or clogging it with unburnt fuel.
  4. Faulty Catalytic Converter: Unfortunately, the catalytic converter itself can degrade over time, especially at 85,000 miles. Internal damage or clogging will reduce its efficiency.

What to do:

  • Step 1: Inspect for Exhaust Leaks: Visually check the exhaust system for any cracks, holes, or loose connections, especially around the manifold and converter.
  • Step 2: Check O2 Sensor Data: If you have an advanced scan tool, monitor live data from both upstream and downstream O2 sensors. The downstream sensor's voltage should be relatively stable compared to the fluctuating upstream sensor if the converter is working properly.
  • Step 3: Address Engine Performance Issues: Ensure there are no other active codes related to misfires (P030x), fuel trim, or engine performance. Resolve these first if present.
  • Step 4: Consider a Fuel System Cleaner: Sometimes, a high-quality fuel system cleaner designed to clean catalytic converters can offer a temporary solution or improve efficiency if the issue is minor carbon buildup.

When to see a shop:

If the code returns after clearing and performing basic checks, or if you don't have the tools to analyze O2 sensor data, it's best to take your CR-V to a qualified mechanic. They can perform a more thorough diagnosis, including backpressure tests and further O2 sensor analysis, to pinpoint whether the issue is a sensor, an exhaust leak, or indeed a failing catalytic converter. Driving with a P0420 for too long, especially if the converter is failing, can lead to reduced fuel economy and potentially more severe engine damage in the long run.

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