P2573: Direct Ozone Reduction Catalyst Deterioration Sensor Circuit Range/Performance
What to do
Nothing will be noticeable in how the car drives, and nothing about the engine is affected. The consequence is that an emissions monitor cannot complete, which matters where that is tested.
Worth knowing: this code is about the sensor, not about the catalyst. A separate code — P2577 — is the one that says the coating itself has stopped working. Fixing a misreporting sensor sometimes makes both go away, so it is the cheaper thing to establish first.
What this code means
The deterioration sensor's signal is electrically valid and implausible — not changing when conditions change, or sitting at a value the module cannot reconcile with what the rest of the system is reporting.
A signal stuck at a believable-looking value is the characteristic failure of this whole family, and it is the reason a range/performance code exists separately from the circuit codes at all. An open circuit announces itself. A sensor that has quietly stopped responding while still producing a plausible number does not, and nothing on the dashboard distinguishes the two.
The cross-check that finds it is the same one described at P2568: compare this system's readings against the ambient air temperature sensor after the vehicle has stood overnight, when everything at the front of the car has had all night to reach the same temperature and ought to agree. Disagreement identifies which sensor is lying.
What this code does not mean is that the catalyst has failed. That verdict is P2577, and confusing the two leads to a part being replaced on the strength of a sensor that was misreporting.
Likely causes
Start here
Less common
- Debris or damage to the radiator coating · moderate
- Physical damage from road debris · moderate
- Damaged wiring harness · moderate
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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