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DTC codes / P25xx · Vehicle speed, idle control and auxiliary inputs / P2569

P2569Direct Ozone Reduction Catalyst Temperature Sensor Circuit Low

P2569 means the powertrain control module (PCM) has detected a low-voltage condition on the signal circuit of the direct ozone reduction (DOR) catalyst temperature sensor. The sensor monitors the temperature of the ozone-reduction catalyst, and the PCM expects a voltage within a specific range; a sustained low reading indicates a short to ground, a faulty sensor, or a wiring problem.

SystemPowertrain
Code typeGeneric (all makes)
SeverityLow
Fix difficultyIntermediate
AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms.
  • A slight decrease in fuel economy if the PCM enters a default mode.
  • In rare cases, a rough idle or hesitation if the fault affects other shared sensor circuits.
  • No driver-perceptible change in performance in most instances.
  • Possible failure of an emissions-related inspection due to the stored code.

Common causes, most likely first

  1. Faulty direct ozone reduction catalyst temperature sensor.
  2. Short to ground in the sensor signal circuit.
  3. Damaged or corroded wiring harness or connector at the sensor.
  4. Water intrusion into the sensor connector causing a short.
  5. PCM internal fault (rare).
  6. Poor ground connection for the sensor circuit.

How to diagnose and fix it

  1. Use an OBD-II scanner to confirm P2569 and check for related codes.
  2. Visually inspect the sensor, connector, and wiring for damage, corrosion, or water intrusion.
  3. Disconnect the sensor and check the signal circuit for a short to ground with a multimeter.
  4. Measure the sensor resistance and compare to the manufacturer's specification.
  5. Check the sensor ground circuit for continuity and proper ground.
  6. If the circuit is intact, replace the sensor with a known-good unit and clear the code.
  7. If the code persists after sensor replacement, diagnose the PCM and its connections.

What P2569 doesn't always mean

  • A low voltage reading at the sensor does not automatically condemn the sensor; a chafed wire shorting to ground often produces the same code.
  • The DOR catalyst temperature sensor is sometimes part of a circuit shared with other sensors, so a fault elsewhere can set P2569 as a secondary code.
  • After replacing the sensor, the PCM may require a relearn or drive cycle before the code clears permanently.
  • Corrosion inside the connector pins is a frequent cause that visual inspection alone can miss; a voltage drop test is more reliable.
  • This code is emissions-related and may not affect driveability, so some technicians overlook it until an emissions test fails.

Can I keep driving with P2569?

The vehicle is generally safe to drive with P2569 because the fault rarely affects performance or safety. Avoid long-term neglect, as continued driving may lead to a failed emissions test or mask a more serious wiring issue.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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