The largest online repair guide library for every car

About us
Contact support
FAQ
Sign up
Sign in

2018 V60 Cross Country Check Engine Light - P0420 Code

0

Brittany E. · rep 0 · May 22, 5:12 AM · 1 replies · solved · Question

Vehicle: 2018 Volvo V60 Cross Country T5

My 2018 Volvo V60 Cross Country has had its check engine light on for a few weeks now. I finally got it scanned, and it's throwing a P0420 code: 'Catalyst System Efficiency Below Threshold (Bank 1)'.

I've tried clearing it, but it comes back after a few drive cycles. The car seems to be running fine, no noticeable loss of power or strange noises, but I know this code usually points to the catalytic converter.

Is there anything else that could cause a P0420 on a Volvo of this age? I'm hoping it's not the catalytic converter itself, as I know those can be expensive to replace. Any common Volvo-specific issues I should look into?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 5:12 AM

0

ClearTheCode admin answer:

The P0420 code on your 2018 Volvo V60 Cross Country, indicating 'Catalyst System Efficiency Below Threshold (Bank 1),' is indeed most commonly associated with a failing catalytic converter. However, it's important to rule out other potential causes before jumping to a costly replacement.

Potential Causes for P0420:

  • Failing Catalytic Converter: Over time, the catalyst material can degrade, reducing its ability to convert harmful exhaust gases efficiently.
  • Faulty Oxygen Sensors: While the code specifically points to catalyst efficiency, a failing upstream (pre-cat) or downstream (post-cat) O2 sensor can provide incorrect readings, leading the ECU to falsely believe the catalyst is inefficient. A P0133 (O2 Sensor Slow Response) or P013E (O2 Sensor Delayed Response) might accompany P0420.
  • Exhaust Leaks: Leaks in the exhaust system before or between the O2 sensors can allow unmetered air in, skewing sensor readings and affecting catalyst monitoring.
  • Engine Misfires or Rich/Lean Conditions: Persistent engine problems like misfires, excessive oil consumption, or running too rich/lean can damage the catalytic converter over time by introducing unburnt fuel or contaminants.
  • Damaged Exhaust Manifold Gasket: A leak here can affect O2 sensor readings.

Diagnostics & Next Steps:

  1. Professional Scan and Live Data: A technician can use a professional scanner to monitor the live data from both upstream and downstream O2 sensors. The waveforms should show distinct patterns; if they mirror each other too closely, it often confirms a failing catalyst.
  2. Exhaust System Inspection: Visually inspect the entire exhaust system for any cracks, holes, or loose connections, especially around the O2 sensors and catalytic converter.
  3. Check for Other Codes: Ensure there are no other active or pending codes related to misfires (P030x), fuel trim (P0171, P0172), or O2 sensor performance (P013x, P014x).
  4. Fuel Quality Check: Ensure you are using the recommended fuel type and quality.

When to See a Shop:

While your car may seem to run fine, a P0420 code indicates increased emissions, which can prevent you from passing inspection. It's best to have a qualified mechanic or Volvo specialist perform a thorough diagnosis. They can accurately test the O2 sensors and the catalytic converter's efficiency to determine the precise cause and recommend the most effective repair, preventing unnecessary part replacements.

Menu

Help & account