Faulty direct ozone reduction catalyst temperature sensor.; Damaged or corroded wiring or connector at the sensor or PCM.; Open or short circuit in the sensor signal or return circuit.; Exhaust system leaks or restrictions altering the sensor's temperature reading.; PCM software calibration issue or internal PCM fault.; Catalyst degradation causing abnormal temperature behavior.

DTC codes / P25xx · Vehicle speed, idle control and auxiliary inputs / P2568

P2568Direct Ozone Reduction Catalyst Temperature Sensor Circuit Range/Performance

P2568 indicates that the powertrain control module (PCM) has detected an out-of-range or erratic signal from the direct ozone reduction catalyst temperature sensor circuit. This sensor monitors the temperature of the catalyst used to reduce ozone emissions, and the PCM sets the code when the sensor voltage or resistance does not correlate with expected values under current operating conditions.

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.
Possible slight decrease in fuel economy due to the PCM entering a default strategy.
In rare cases, a rough idle or hesitation if the faulty circuit affects other shared sensor references.
No driver-perceptible change in performance in most instances.
Intermittent warning light that may clear and reset after key cycles.

Common causes, most likely first

Faulty direct ozone reduction catalyst temperature sensor.
Damaged or corroded wiring or connector at the sensor or PCM.
Open or short circuit in the sensor signal or return circuit.
Exhaust system leaks or restrictions altering the sensor's temperature reading.
PCM software calibration issue or internal PCM fault.
Catalyst degradation causing abnormal temperature behavior.

How to diagnose and fix it

Connect a scan tool and record freeze-frame data to see when the code set.
Visually inspect the sensor, connector, and wiring for damage or corrosion.
Measure sensor resistance and compare to manufacturer specifications.
Check for exhaust leaks or restrictions near the catalyst.
Perform a voltage drop test on the sensor signal and ground circuits.
If all checks pass, reprogram the PCM with the latest calibration.
Replace the sensor only after confirming the circuit and catalyst are functioning correctly.

Before you replace the ozone sensor

A P2568 can be set by a simple loose connector that intermittently loses contact, so always wiggle-test the harness while monitoring live data.
The ozone reduction catalyst temperature sensor is often confused with the standard catalytic converter temperature sensor, but they serve different emission control strategies.
Exhaust leaks upstream of the sensor can cause temperature readings to be lower than expected, mimicking a sensor failure.
Some vehicles require a PCM relearn or calibration update after sensor replacement to prevent the code from returning.
The code does not always mean the sensor is defective; a failing thermostat or cooling system issue can alter exhaust temperatures and trigger it.

Can I keep driving with P2568?

The vehicle is generally safe to drive with P2568 because it does not affect engine performance or safety systems, but have it diagnosed soon to ensure the ozone reduction system functions correctly and to avoid potential emissions test failure.

Tools that help

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