What it means
The Direct Ozone Reduction Catalyst Temperature Sensor Circuit Low code indicates the sensor circuit signal is below its expected lower limit. It identifies a circuit fault; the precise cause depends on the vehicle.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The direct ozone reduction catalyst temperature sensor sends a signal used by the control module to monitor the emissions catalyst. This code sets when that signal falls below its expected electrical lower limit, which can result from a signal wire shorted to ground, an internally shorted sensor, or a poor connection.
Common causes
Most likely first.
- Signal wire shorted to ground
- Sensor shorted internally
- Connector pins corroded - high contact resistance
Symptoms
- Check engine light
How to diagnose it
- Record freeze-frame data and check the catalyst temperature sensor's live reading for a persistently low or implausible value.
- Inspect the direct ozone reduction catalyst sensor connector and nearby harness for corrosion, water intrusion, chafing, or heat damage.
- Check the signal wire for a short to ground and inspect connector pins for poor contact.
- Verify the sensor's reference or supply and ground circuits against the manufacturer's specification.
- If the wiring is intact, test the temperature sensor and control-module circuit using the vehicle wiring diagram and specified procedure.
Common fixes
- Clean and secure corroded or loose sensor connector terminals.
- Repair a signal wire shorted to ground or damaged by chafing.
- Replace the catalyst temperature sensor if it is internally shorted.
- Restore a faulty sensor supply or ground connection.
Can I keep driving?
A short trip may be manageable if the engine runs normally, but emissions monitoring can be affected and the vehicle may fail an emissions test. Arrange repair soon and stop if reduced power or signs of exhaust overheating develop.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.