Open or high-resistance ground circuit at the ozone reduction catalyst deterioration sensor; Short to voltage on the sensor signal circuit, often from chafed insulation against a nearby power wire; Failed ozone reduction catalyst deterioration sensor internally shorted to its supply voltage; Corroded or loose electrical connector at the sensor or at the PCM; PCM internal fault driving the signal circuit reference voltage too high; Aftermarket or incorrect sensor installed that does not match the OEM voltage characteristics

DTC codes / P25xx · Vehicle speed, idle control and auxiliary inputs / P2575

P2575Direct Ozone Reduction Catalyst Deterioration Sensor Circuit High

P2575 indicates that the powertrain control module has detected an abnormally high voltage on the signal circuit of the direct ozone reduction catalyst deterioration sensor, which is used to monitor the catalyst's ability to reduce ozone. The sensor circuit is typically a low-voltage reference and signal return, so a high-voltage reading means the PCM sees a short to voltage, an open ground, or a sensor that has failed in a way that drives the signal high.

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
Slightly reduced fuel economy if the PCM enters a default strategy for the ozone reduction system
In rare cases, a message in the driver information center about an emissions system fault
No change in engine performance or drivability, because the ozone reduction catalyst is an emissions-only system
Intermittent warning light if the high-voltage condition is caused by a loose connector or chafed wire

Common causes, most likely first

Open or high-resistance ground circuit at the ozone reduction catalyst deterioration sensor
Short to voltage on the sensor signal circuit, often from chafed insulation against a nearby power wire
Failed ozone reduction catalyst deterioration sensor internally shorted to its supply voltage
Corroded or loose electrical connector at the sensor or at the PCM
PCM internal fault driving the signal circuit reference voltage too high
Aftermarket or incorrect sensor installed that does not match the OEM voltage characteristics

How to diagnose and fix it

Connect a scan tool and record the freeze-frame data and sensor voltage reading to confirm the high-voltage condition
Visually inspect the sensor connector and wiring for corrosion, loose pins, or chafed insulation, and repair as needed
Measure resistance of the sensor ground circuit from the sensor connector to the PCM ground pin to check for an open ground
With the key on and sensor disconnected, measure voltage on the signal circuit at the sensor harness connector to check for a short to voltage
Check the sensor's internal resistance or voltage output against the manufacturer's specification, and replace the sensor if it is out of range
Clear the diagnostic trouble codes and perform a road test to verify the repair and confirm the code does not return
If all external circuits and the sensor test good, follow the manufacturer's diagnostic flow for a possible PCM fault before replacing the PCM

What the ozone sensor code really means

A high-voltage code on this sensor is more often a wiring or ground problem than a failed sensor, so resistance and voltage-drop tests on the ground circuit should come before parts replacement.
The direct ozone reduction catalyst deterioration sensor is not the same as a downstream oxygen sensor, and testing it with oxygen-sensor procedures will give misleading results.
Because the ozone reduction system has no effect on engine performance, many vehicles with P2575 drive normally and the only clue is the warning light, which leads owners to postpone diagnosis until an emissions test fails.
A weak or corroded ground connection at the catalyst mounting point can elevate the signal voltage without any visible damage to the sensor itself.
Some scan tools show this sensor's voltage in a live data stream that updates slowly, so a single snapshot can miss an intermittent short that only appears when the harness is flexed.

Can I keep driving with P2575?

The vehicle remains safe to drive because this fault affects only an emissions control system and does not alter engine operation, but you should avoid long delays in diagnosis if your area requires an emissions inspection. Have the circuit checked at the next convenient opportunity to prevent the warning light from masking a more serious fault.

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.