P2577
Direct Ozone Reduction Catalyst Efficiency Below Threshold
- Severity
- Low
- Driving
- No driving restriction
The direct ozone reduction catalyst is not converting as well as it should. A direct ozone reduction catalyst is a coating on the radiator, not part of the exhaust. Air passing through the radiator is converted from ground-level ozone into oxygen, so the vehicle cleans a little of the air it drives through. It is fitted to a small number of very low emission vehicles and has no effect on how the engine runs. The coating wears out over time and is also degraded by debris and contamination on the radiator face.
Possible causes
- CommonFailed sensor
- CommonCorroded or water-ingressed connector at the front of the vehicle
- CommonWiring damage from stone strikes or road debris
- PossibleRadiator coating damaged or contaminated
- PossibleLoss of reference voltage or earth
- PossibleFront-end damage or repair disturbing the wiring
- CommonCoating worn out with age and mileage
- CommonRadiator face blocked with leaves, insects or road debris
- CommonRadiator replaced with one lacking the coating
What you might notice
- Check engine light on
- Failed emissions test in jurisdictions that test for it
- No effect on how the car drives
- No symptom the driver notices
What to check, in order
- Check the radiator face is clear. A radiator packed with debris cannot pass air through the coating, and clearing it is free.
- Ask whether the radiator has been replaced. A standard replacement has no coating, and this code is the inevitable result.
- Read all codes - sensor codes alongside this one mean the measurement rather than the coating may be at fault.
- Note that this has no effect on how the engine runs. It matters for an emissions test and for nothing else.
Read this code from your own car
Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.
Where this code sits
Vehicle speed control, idle control and auxiliary inputs