Failed direct ozone reduction catalyst temperature sensor; Open or damaged signal wire between the sensor and the engine control module; Short to voltage on the sensor signal circuit; Corroded or loose electrical connector at the sensor or computer; Faulty engine control module (less common); Exhaust system damage or modification that affects sensor mounting

DTC codes / P25xx · Vehicle speed, idle control and auxiliary inputs / P2570

P2570Direct Ozone Reduction Catalyst Temperature Sensor Circuit High

P2570 means the engine computer has detected an abnormally high voltage on the signal circuit of the direct ozone reduction catalyst temperature sensor, which is used on vehicles with a special ozone-reducing catalyst to monitor its temperature. The computer expects the sensor's voltage to stay within a calibrated range, and a sustained high reading tells it the circuit is likely open, shorted to voltage, or the sensor itself has failed.

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 or driveability if the fault affects catalyst monitoring
Possible failure of an emissions inspection due to the stored code
In rare cases, a message or warning related to the emissions system on the dashboard
No change in engine performance because the sensor is for emissions monitoring, not engine control

Common causes, most likely first

Failed direct ozone reduction catalyst temperature sensor
Open or damaged signal wire between the sensor and the engine control module
Short to voltage on the sensor signal circuit
Corroded or loose electrical connector at the sensor or computer
Faulty engine control module (less common)
Exhaust system damage or modification that affects sensor mounting

How to diagnose and fix it

Connect a scan tool and record the freeze-frame data and any related codes to confirm the fault conditions
Visually inspect the sensor, its wiring, and connectors for damage, corrosion, or loose pins
Measure the sensor's resistance and compare it to the manufacturer's specification to check for an open or shorted element
Back-probe the signal circuit at the sensor and at the computer to check for an open or a short to voltage with the key on
If the wiring and connectors are good, replace the sensor with a known-good unit and clear the code
After repair, clear the codes and perform a drive cycle to verify the repair and ensure the monitor runs to completion
If the code returns, check the computer's reference voltage and ground circuits, and inspect for intermittent faults

What the ozone sensor code really means

This sensor is only fitted to vehicles with a direct ozone reduction catalyst, so the code will not appear on most cars and is often misdiagnosed as a generic catalyst efficiency fault.
A high voltage reading does not always mean the sensor is bad; a simple chafed wire shorting to a nearby power source can set the same code.
Technicians sometimes replace the catalytic converter unnecessarily because they confuse this temperature sensor code with a catalyst efficiency code like P0420.
The sensor's signal circuit is very low current, so even a small amount of corrosion or water intrusion in a connector can cause a high-voltage fault.
Always check for technical service bulletins (TSBs) for the specific vehicle, as some manufacturers have updated sensor designs or wiring harness routing to prevent this code.

Can I keep driving with P2570?

The vehicle remains safe to drive because this sensor only monitors emissions system temperature and does not affect engine operation, but you should avoid long delays in repair to prevent failing an emissions test. Have the fault diagnosed soon, especially if your area requires annual inspections.

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.