P2571 OBD-II Trouble Code: Direct Ozone Reduction Catalyst Temperature Sensor Circuit 4 Intermittent/Erratic

Check Engine Light

P2571 code definition

A P2571 trouble code indicates that the Powertrain Control Module (PCM) has detected higher-than-normal voltage from the direct control ozone reduction catalyst temperature sensor.

Other related trouble codes include P2567, P2568, P2569, P2570, P2572, P2573, P2574, P2575, P2576, and P2577 codes.

What the P2571 code means

A P2571 trouble code means that the direct ozone reduction catalyst temperature sensor has failed to detect the correct temperature, leading to the storage of a P2571 code in the PCM and the illumination of the Check Engine light.

What causes the P2571 code?

While the most common cause of a P2571 trouble code is a faulty direct o-zone reduction catalyst temperature sensor, there are also some other causes for storage of this trouble code in the PCM, including:

  • A bad oxygen sensor, though this also causes an oxygen sensor to also be stored.
  • A leak in the exhaust manifold, down pipe, flex hose, or other exhaust components upstream from the direct ozone reduction catalyst sensor.

What are the symptoms of the P2571 code?

Symptoms of a P2571 trouble code are most commonly the storage of the code in the PCM and illumination of the Check Engine light. Some other symptoms sometimes found with a P2571 trouble code are a no start condition, an engine stall condition, engine hesitation, lowered engine performance, and a hissing noise while accelerating.

How does a mechanic diagnose the P2571 code?

The mechanic should have an advanced scanner, oscilloscope, digital volt/ohmmeter, and a temperature gun to correctly diagnose a P2571 code. To repair and clear a P2571 trouble code, the mechanic should perform the following diagnostic steps:

  • Inspect the entire exhaust system for leaks.

  • Retest the system after repairing any detected leaks.

  • The mechanic should also visually inspect any wiring and connectors.

  • After repairing any faulty or damaged wiring and connectors, the mechanic should clear the code and retest the system to see if the trouble code returns.

  • In addition, the mechanic can raise the vehicle and inspect the exhaust pipe underneath, using the temperature gun to test the points directly before and after the suspected faulty direct ozone reduction catalyst device. The mechanic should compare their findings to the manufacturer's specifications.

  • Using the advanced scanner and oscilloscope, the mechanic should monitor the downstream and upstream oxygen sensors in the affected bank to see if any discrepancies are detected.

  • Start the vehicle and allow the engine to reach a normal operating temperature.

  • Putting the vehicle into idle, wait for the engine control system to enter closed loop operation and then test the voltage at the upstream oxygen sensor. Then test the downstream oxygen sensor.

  • The voltage on both sensors should be within manufacturer's specifications, with the upstream sensor having a little fluctuation and the downstream sensor having none.

  • If any fluctuations are detected with the downstream sensor, then the catalytic converter is most likely at fault.

  • If either or both sensors are slow to respond, then most likely one or both of the sensors are at fault.

  • Repair or replace any faulty components before test driving the vehicle to further test the system and see if the trouble code returns.

Common mistakes when diagnosing the P2571 code

A common misdiagnosis of a P2571 trouble code is caused by not determining what initiated the code to be stored in the first place. By just replacing a faulty direct ozone reduction catalyst temperature sensor and not fixing what caused the sensor to go bad in the first place means that the replacement sensor will more than likely go out again with the code reappearing.

How serious is the P2571 code?

A P2571 trouble code means the direct ozone reduction catalyst temperature sensor is not working properly and is a sign of other problems within the catalytic converter system. If left unrepaired, it can lead to lowered engine performance, misfires, stalling, and hesitation. This code can also lead to higher emissions from your vehicle exhaust

What repairs can fix the P2571 code?

Once diagnosed, in order to properly fix and clear a P2571 trouble code, the mechanic must perform the following:

  • Repair any detected leaks in the exhaust system
  • Repair or replace any damaged or faulty connectors, wiring, and/or components
  • Replace any faulty upstream or downstream oxygen sensors
  • Replace the faulty direct ozone reduction catalyst temperature sensor
  • In extreme cases, replace the catalytic converter if it is the problem

Additional comments for consideration regarding the P2571 code

Before replacing the direct ozone reduction catalyst temperature sensor, the mechanic should make sure all oxygen sensors are also working properly and replace those first. In the case of a bad or failing oxygen sensor, the mechanic should also find an related oxygen sensor code stored on the PCM. In addition, they should make sure that the direct ozone reduction catalyst is not under a manufacturer's warranty before beginning diagnosis.

Need help with a P2571 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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