P2574 OBD-II Trouble Code: Direct Ozone Reduction Catalyst Deterioration Sensor Circuit Low4

Check Engine Light

P2574 code definition

A P2574 trouble code is an indication that the direct ozone reduction catalyst deterioration sensor or circuit has encountered a varying degree of voltage. The Powertrain Control Module (PCM) has thus stored the trouble code and has illuminated the Check Engine Light. In addition to the P2574 trouble code, mechanics should look for the following, related trouble codes, including P2567, P2568, P2569, P2570, P2571, P2572, P2573, P2575, P2576, and P2577.

What the P2574 code means

Using data from the upstream and downstream oxygen sensors, the PCM calculates the degree of ozone reduction for each catalytic converter. When this amount is not where it should be, a P2574 trouble code gets stored on the PCM and the Check Engine Light illuminates.

What causes the P2574 code?

A faulty direct ozone reduction catalyst deterioration sensor is the most common reason for storage of this trouble code. If a bad oxygen sensor is the culprit, the mechanic should expect an oxygen sensor code to accompany the P2574 code. The mechanic should also look for contributing factors that can cause this code since a direct ozone reduction catalytic converter is not designed to wear out. These contributing factors include a faulty mass flow, coolant temperature, or manifold air pressure sensor; problems with fuel quality or the fuel system; and issues with the ignition system, such as incorrect spark timing or an ignition misfire. Finally, a leak in the exhaust system can sometimes fool the PCM into thinking that the direct ozone reduction catalyst has failed.

What are the symptoms of the P2574 code?

Symptoms of a P2574 trouble code run the gamut from only a code storage followed by an illumination of the Check Engine Light to a no start or engine stall condition. Vehicle drivability can become an issue as well, with engine hesitation, poor performance, or a hissing sound present upon acceleration common problems with advanced forms of the conditions that cause this code.

How does a mechanic diagnose the P2574 code?

Diagnosing a P2574 trouble code is an involved process starting with an inspection of the exhaust system for any leaks. If no leaks are detected, a mechanic should use a OBD-II code scanner, temperature gun, and digital volt/ohmmeter for further diagnosis. When diagnosing a P2574 trouble code, perform the following steps:

  • Visually inspect all wiring, connectors, and components, looking for any damage.
  • If the code persists, the mechanic should raise the vehicle to check the temperature before and after the direct ozone reduction catalyst device and compare the readings to the manufacturer's specifications.
  • If the direct ozone reduction catalyst device checks out, use the OBD-II scanner and oscilloscope to test the upstream and downstream oxygen sensors.
  • Start the engine and allow the vehicle to reach a normal operating temperature.
  • Depending on the actions of the upstream and downstream oxygen sensors determines if the catalytic converter or one of the sensors is at fault.
  • Upon repairing or replacing the component at fault, clear the code, and retest the system to see if the code reappears.

Common mistakes when diagnosing the P2574 code

Leaving the underlying cause of the storage code untreated can lead to repeated reoccurrences of a P2574 trouble code. Mechanics should repair and clear related trouble codes first before trying to clear a P2574 trouble code. They can determine the order of the storage of various trouble codes by downloading the freeze frame data and any stored codes from the PCM.

How serious is the P2574 code?

The storage of a P2574 trouble code can lead to, among other things, a engine no start or stalling condition. Sometimes, engine hesitation, lowered performance, and problems with acceleration also accompany this code.

What repairs can fix the P2574 code?

Once a diagnosis has been made by the mechanic, they should attempt to repair the problem in order to clear the code, including the following repairs:

Additional comments for consideration regarding the P2574 code

Before attempting to diagnose a P2574 trouble code, the mechanic should check to ensure that the direct reduction catalyst is not under warranty, with many having a 100,000-mile federally mandated warranty.

Need help with a P2574 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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