Direct Ozone Reduction Catalyst Deterioration Sensor Circuit Low

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

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

1. Inspect the connector and wiring at the front of the vehicle. This equipment sits behind the grille and takes stone strikes, water and road salt.
2. Ask whether the vehicle has had front-end damage or a radiator replaced. A replacement radiator without the coating, or with the sensor left disconnected, produces exactly this.
3. Check the reference voltage and earth at the sensor.
4. Check the radiator face is clear of debris.
5. Note that this system has no effect on how the engine runs, so it can be dealt with at convenience unless an emissions test is due.