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P0420
2016 Honda Accord
Honda
Severity
Medium
Safe to Drive
Yes
Est. Time
1hr
Difficulty
Easy
SYMPTOM
Check engine light, no drivability issues
Why This Happens
Honda's catalyst monitor is highly sensitive to upstream sensor drift, so sensor aging often triggers this code before the converter has actually lost efficiency.
VERIFIED FIX:
Upstream O2 sensor replaced
How It Was Diagnosed
Honda's catalyst monitor is highly sensitive to upstream sensor drift, so sensor aging often triggers this code before the converter has actually lost efficiency.
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