P2573

Code

Generic P — Powertrain

Direct Ozone Reduction Catalyst Deterioration Sensor Circuit Range/Performance

Brand: Generic

Type: P — Powertrain

Views: UK: 30 EN: 23 RU: 22

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Page language: EN

Causes

Faulty ozone reduction catalyst deterioration sensor (open, shorted, contaminated, or aged)
Damaged, corroded, or disconnected sensor connector or wiring (open, short to ground or battery, high resistance)
Poor power or ground to the sensor (fused power or ground circuit fault)
Heater element failure in sensor (if equipped)
Contaminated or failing ozone reduction catalyst affecting sensor readings
PCM/ECM software or internal fault (less common)

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Possible failed emissions test
No obvious drivability symptoms in many cases (system monitors emissions performance)
Reduced ozone reduction performance (not always noticeable to driver)
Diagnostic trouble code stored and freeze frame data available

What to check

Scan for stored codes and freeze-frame, note any related codes (O2, catalyst, HVAC emissions)
Perform visual inspection of sensor, wiring, and connectors for damage, corrosion, or contamination
Back-probe sensor connector and check reference voltage (typically 5 V logic reference or 12 V for heater) and ground integrity
Measure sensor signal voltage or waveform with all operating conditions (key ON, engine idling, commanded heater on)
Check continuity and resistance of sensor heater circuit (if equipped) and compare to spec
Wiggle wiring harness while monitoring live data to reproduce fault

Signal parameters

Sensor signal typically operates within 0–5 V range; exact expected idle/run values depend on sensor type
Reference supply (if used) commonly 5 V regulated from the PCM/ECU
Heater circuit (when present) expects battery voltage when commanded (approx. 12 V) and normal heater resistance per manufacturer spec
Signal should change with engine/temperature load and should not be stuck at fixed value or rapidly oscillating outside expected range
Continuity of signal/ground circuits should be near 0 ohms (low resistance); open or high resistance will affect readings

Diagnostic algorithm

Retrieve P2573 and any related codes. Record freeze frame and live data.
Perform a thorough visual inspection of the sensor, harness, and connector. Repair visible damage.
With key ON (engine OFF), back-probe the connector and verify reference voltage and ground. If reference is missing, trace and repair source.
Start engine and monitor sensor signal with a DVOM or scope. Compare live values/waveform with expected behavior (should vary with engine conditions).
Test heater circuit (if equipped): measure resistance with sensor disconnected and verify PCM supplies power when commanded.
Check continuity and resistance of signal, power and ground wires between sensor and PCM. Repair any short/open.

Likely causes

Broken or corroded connector at sensor
Sensor internal failure or contamination
Shorted signal wire to ground or to 12V
Open reference voltage or ground to sensor
Failed heater circuit in the sensor

Fault status

⚠️ Status

The control module has detected the Direct Ozone Reduction Catalyst Deterioration Sensor circuit is out of its expected range or performance. The system has set DTC P2573 and illuminated the MIL. Inspect sensor, wiring, and related components; test and repair as required.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 3.0 hours