P2573 — Direct Ozone Reduction Catalyst Deterioration Sensor Circuit

Introduction:
The diagnostic trouble code (DTC) P2573 indicates an issue with the circuit related to the sensor that monitors the deterioration of the Direct Ozone Reduction Catalyst. In simple terms, this sensor helps manage emissions by measuring the health of a component that reduces ozone emissions in the vehicle’s exhaust system. When this code appears, it suggests a problem with the sensor’s electrical circuit, wiring, or the sensor itself.

Note: The exact label for this trouble code may vary depending on the vehicle’s manufacturer or model. Always refer to the vehicle-specific repair information or OEM documentation for precise codes.

Fast Facts

System affected: Emissions control — Ozone reduction catalyst monitoring
Severity: Moderate — recommended to diagnose and repair promptly
Main symptoms: Check Engine Light (CEL) illuminated, possible emissions-related issues, írregular idle
Driveability: Limited — the vehicle may still operate but with potential emissions or engine performance concerns

Manufacturer variations for trouble code P2573

The labeling of the P2573 code can differ between vehicle manufacturers, as each OEM may assign its own specific diagnostic label. These labels are embedded within their onboard diagnostic systems and can sometimes be vehicle-specific. Here are some known variations:

Honda / Acura: P2593 — Deterioration Sensor Circuit for Selective Catalytic Reduction (SCR) or Diesel Particulate Filter (DPF) systems
Volkswagen / Audi / Seat / Skoda: 226B — Ozone Reduction Catalyst Deterioration Sensor Circuit
BMW: 4D77 — Sensor Circuit for Emissions Catalyst Deterioration
Mercedes-Benz: A0276 — Catalyst Deterioration Sensor Circuit

> **Always consult the specific repair manual or diagnostic information for the exact label used by the vehicle’s manufacturer.**

What does trouble code P2573 mean?

P2573 signifies that the vehicle’s engine control unit (ECU) has detected a malfunction in the circuit related to the direct ozone reduction catalyst deterioration sensor. This sensor plays a crucial role in measuring the performance of the component responsible for reducing ozone emissions in the exhaust flow. When the sensor circuit shows irregularities—such as voltage inconsistencies, open circuits, or short circuits—the ECU interprets this as a deterioration condition or a fault in the sensor circuit.

Generally, this code is triggered when the ECU receives signals that deviate from the expected range, indicating that the sensor might be malfunctioning, damaged, or disconnected. The malfunction could also stem from problems in the wiring, connectors, or related components.

Typically, this issue appears during routine emissions testing, after a component replacement, or sometimes due to aging wiring or sensor failure. It is often detected during the vehicle’s self-diagnostic procedures, especially if the emission system’s monitoring thresholds are exceeded.

Severity and risks of trouble code P2573

The negative implications of a P2573 are primarily environmental and diagnostic. A malfunctioning ozone reduction catalyst sensor may lead to inaccurate readings, causing the ECU to mismanage emissions system functions. This can result in increased emissions, potential failure of emissions testing, and possible impact on engine performance if related system controls are affected.

In terms of risks, lingering faults might lead to a gradual deterioration of the catalyst’s efficiency, with long-term effects on vehicle emissions and potential damage to emissions components. However, in most cases, this code does not directly threaten engine safety or drivability.

Can the vehicle be driven? — Yes, but with caution. The vehicle can typically still operate, but emissions and efficiency might be compromised. It is advisable to diagnose and repair the issue promptly.

Symptoms of trouble code P2573

While this code is often discovered through diagnostic tools, some drivers may notice associated symptoms indicating the need for inspection. Common symptoms include:

Illumination of the Check Engine Light (CEL)
Reduced fuel efficiency
Unusual exhaust smell or increased emissions
Intermittent or rough engine idle
Possible loss of power or hesitation during acceleration
Failure to pass emissions testing

Most likely causes of trouble code P2573

Understanding what can trigger this fault helps streamline diagnosis. The causes are typically related to electrical or sensor-related issues. The most common causes include:

Damaged or faulty ozone reduction catalyst deterioration sensor — Over time, sensors can fail due to aging or exposure to high exhaust temperatures.
Wiring issues — Frayed, broken, or corroded wiring or connectors can cause intermittent or open circuits that trigger the code.
Electrical connection problems — Loose or poor connections at the sensor or ECU interface points can lead to signal faults.
Contaminated or poisoned sensor — Exposure to engine additives or environmental factors may impair sensor function.
ECU software or calibration issues — Rare, but possible, especially after repairs or updates.

How to diagnose trouble code P2573

Diagnosing this code involves systematic checks to isolate the fault. Here are the general steps:

Visual inspection: Examine the sensor, wiring, and connectors for damage, corrosion, or loose connections.
Check wiring continuity: Use a multimeter to verify that wiring between the sensor and ECU is intact and free of shorts or open circuits.
Test the sensor voltage signal: Measure the sensor’s output voltage while the engine is running to see if it falls within the specified range indicated in the repair manual.
Inspect for contamination or damage: Ensure the sensor has not been contaminated or physically damaged.
Clear codes and perform a road test: Reset the ECU codes and then conduct a test drive to verify if the code reappears and to observe live data readings.

Possible repairs for trouble code P2573

If you experience this fault, a series of repairs could resolve the issue. The appropriate repair depends on the root cause determined during diagnostics. Here are typical potential repairs:

Replace the ozone reduction catalyst deterioration sensor — Basic repair, generally requiring a professional if specialised tools or calibration are necessary.
Repair or replace damaged wiring or connectors — Basic repair that can be performed by an experienced technician.
Ensure proper electrical connections: Tighten or reseat connectors to ensure solid contact.
Clean or replace contaminated sensors: Only recommended if contamination is confirmed, otherwise sensor replacement is advised.
Update ECU software or re-calibrate sensors: Typically a professional repair requiring OEM tools.

Vehicles commonly associated with trouble code P2573 in Europe

This code can appear across various vehicle makes, particularly those with advanced emissions control systems. Based on available data, the following brands are more prone to experiencing this fault:

European brands:

Volkswagen Group (Volkswagen, Audi, Škoda, Seat)
BMW
Mercedes-Benz

Within these brands, particular engines or model years might be more affected, especially those equipped with advanced emission reduction systems involving ozone or SCR components.

Frequent mistakes with trouble code P2573

Diagnosing and repairing emission-related codes like P2573 can be tricky. Common errors include:

Misinterpreting sensor signals: Relying solely on live data without considering the context or sensor calibration can lead to incorrect diagnoses.
Overlooking wiring inspections: Assuming the sensor is faulty without checking wiring and connections often results in unnecessary part replacements.
Ignoring environmental factors: Contamination or exposure to harsh conditions can mimic electrical faults, leading to unneeded repairs.
Resetting codes prematurely: Clearing codes without fixing underlying issues can result in the fault reappearing shortly after.

FAQ — trouble code P2573

Can this code disappear on its own?
Usually, no. Once the fault triggers the ECU to set the code, it generally remains until the underlying issue is addressed. Some temporary wiring issues or transient faults might resolve themselves, but persistent faults require diagnosis and repair.

Can I keep driving?
In most cases, yes. The vehicle can usually operate normally, though emissions performance may be compromised. It is advisable to get the issue checked promptly to avoid long-term damage and ensure compliance with emissions regulations.

Why does the code return after clearing it?
The code reappears because the ECU continues detecting the same fault condition. Clearing codes resets the warning, but if the root cause isn’t fixed, the fault will likely reoccur during subsequent driving cycles.