Faulty direct ozone reduction catalyst deterioration sensor.; Damaged or corroded wiring or connector at the sensor.; Open or short circuit in the sensor signal or ground circuit.; Exhaust leak near the sensor affecting its reading.; Catalyst deterioration or contamination causing the sensor to read out of range.; PCM software issue or internal fault (less common).

DTC codes / P25xx · Vehicle speed, idle control and auxiliary inputs / P2573

P2573Direct Ozone Reduction Catalyst Deterioration Sensor Circuit Range/Performance

P2573 indicates that the powertrain control module (PCM) has detected an out-of-range or performance fault in the circuit for the direct ozone reduction catalyst deterioration sensor. This sensor monitors the condition of the catalyst that reduces ozone, and the PCM sets the code when the sensor signal does not behave as expected under normal 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 if the fault affects air-fuel ratio control.
In rare cases, a rough idle or hesitation during acceleration if the sensor signal is erratic.
No driver-perceptible change in vehicle performance in most instances.
Failure to pass an emissions inspection due to the stored code.

Common causes, most likely first

Faulty direct ozone reduction catalyst deterioration sensor.
Damaged or corroded wiring or connector at the sensor.
Open or short circuit in the sensor signal or ground circuit.
Exhaust leak near the sensor affecting its reading.
Catalyst deterioration or contamination causing the sensor to read out of range.
PCM software issue or internal fault (less common).

How to diagnose and fix it

Use an OBD-II scanner to verify the code and check for any related pending or history codes.
Visually inspect the sensor, its wiring, and connector for damage, corrosion, or loose pins.
Check the sensor's resistance and signal voltage with a multimeter according to the manufacturer's specifications.
Inspect the exhaust system for leaks or damage near the sensor that could skew readings.
Test the sensor circuit for continuity and shorts to ground or power.
If the sensor and wiring are good, check for catalyst efficiency issues using live data or a scan tool.
Replace the sensor or repair wiring as needed, then clear codes and verify the repair with a test drive.

Before replacing the ozone sensor

A common mistake is to replace the sensor without checking the wiring harness, as chafed or corroded wires often cause this code.
Exhaust leaks upstream of the sensor can introduce outside air and cause a range/performance fault that mimics a bad sensor.
The direct ozone reduction catalyst is separate from the main catalytic converter, so don't assume the primary converter is at fault.
On some vehicles, this code may be set by a software glitch in the PCM, and a reflash may be required after parts replacement.
Always check for technical service bulletins (TSBs) for your specific make and model, as pattern failures are common.

Can I keep driving with P2573?

The vehicle is generally safe to drive with this code, as it rarely affects drivability. However, avoid long-term driving with the check engine light on, as it may prevent you from passing emissions testing and could mask other developing issues.

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.