P2571

Code

Generic P — Powertrain

Direct Ozone Reduction Catalyst Temperature Sensor Circuit Intermittent/Erratic

Brand: Generic

Type: P — Powertrain

Views: UK: 19 EN: 42 RU: 28

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Intermittent/open/shorted wiring between sensor and control module
Corroded, loose, or damaged connector at the sensor or module
Damaged sensor (internal failure)
Intermittent ground or reference voltage to the sensor
Harness chafing or heat damage from nearby components
Intermittent ECM/input circuit fault or poor mating at the ECM connector

Symptoms

Malfunction Indicator Lamp (MIL) or Check Engine Light illuminated
Stored intermittent/erratic catalyst temperature sensor DTC
Possible failed or incomplete emissions readiness monitors
No obvious drivability symptoms in many cases (engine may run normally)
Occasional transient faults in emissions-related diagnostics

What to check

Read and record freeze frame and all related freeze/live data using a scan tool
Check for additional related codes (other sensor or catalyst codes)
Perform a visual inspection of sensor, connector, and wiring for damage, corrosion, burns, or chafing
Backprobe the sensor connector and observe live signal with scan tool or DMM while engine warms and cools
Wiggle test wiring harness while watching live data for intermittent changes
Inspect and verify good power supply and ground for the sensor circuit at the connector and ECM

Signal parameters

Sensor signal should be stable and change smoothly with temperature; not jumpy or random
Typical sensor circuit voltage range: approximately 0.1–4.9 V (vehicle-specific values vary)
Sensor resistance vs. temperature should be monotonic (thermistor-type sensors decrease or increase resistance steadily with temperature)
Reference power (if used) should be steady (typically a regulated 5 V reference) and not intermittent
No repeated short-duration dropouts or random spikes in the recorded waveform

Diagnostic algorithm

Connect a diagnostic scan tool; confirm P2571 and record freeze frame and live data. Note ambient and catalyst temperatures at fault.
Perform visual inspection: check sensor connector, wiring harness routing, signs of heat damage, corrosion, or recent repairs.
Backprobe sensor harness: verify reference voltage (if applicable), sensor signal voltage, and ground while engine off and running. Compare to expected steady values.
Perform wiggle test: with connector connected and engine at operating temp, wiggle harness and connector while watching live data for intermittent changes. If fault repeats, identify point of harness movement producing fault.
Measure sensor resistance (with sensor disconnected) at known ambient temperature and while warming (if safe). Expect smooth, predictable change — consult vehicle-specific spec. If sensor resistance varies erratically, replace sensor.
If signal looks noisy or has dropouts, use an oscilloscope to capture waveform while reproducing the fault; look for intermittent opens, shorts, or electrical noise.
Inspect and test connector pins for continuity to the ECM. Repair any broken wires, poor crimps, or damaged pins. Check for water intrusion or corrosion and repair with proper terminals/seals.
Check ECM connector for bent pins or poor mating; perform wiggle test at the ECM if safe.
Repair or replace damaged wiring, connector, or sensor as indicated. Use heat-protected routing and secure harness away from exhaust or hot surfaces.
Clear codes and perform drive/monitoring cycle to confirm repair and that the intermittent condition does not return. If code returns, re-evaluate ECM and wiring grounds, or consult vehicle-specific technical service information.

Likely causes

Loose or corroded connector at the temperature sensor
Damaged sensor harness insulation with intermittent short to ground or intermittent open
Sensor internal intermittent fault due to heat cycling or contamination
Poor or intermittent ground or 5V reference to the sensor
Intermittent connector contact at ECM