P214D

Code

Generic P — Powertrain

SCR NOx Catalyst Outlet Temperature Too High During Particulate Filter Regeneration

Brand: Generic

Type: P — Powertrain

Views: UK: 19 EN: 34 RU: 20

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Page language: EN

Causes

Excessive exhaust temperature during forced or active DPF regeneration (overfuelling or excessive dosing)
Failed or intermittent SCR/NOx catalyst outlet temperature sensor (thermistor/thermocouple)
Damaged, corroded or shorted wiring or poor connector connection to the temperature sensor
Sensor contaminated by soot, oil or deposits or physically displaced from its mounting location
Faulty engine management control of regeneration (ECM software/calibration or injector control)
Aftermarket modifications or clogged/excessive backpressure in exhaust increasing temperatures

Symptoms

Malfunction Indicator Lamp (MIL) or fault light on
Recorded DTC present under or after a DPF regeneration event
Possible aborted or suspended regeneration cycles
Reduced engine performance or limp-home mode in some vehicles
Increased fuel consumption or visible soot/black smoke during failed regen
Freeze frame data showing elevated exhaust temperature at time of fault

What to check

Read and record stored DTCs and freeze frame data with a capable scan tool
Inspect sensor connector and wiring for corrosion, chafing, heat damage or loose pins
Visually inspect sensor installation and mounting location for contamination or displacement
Compare downstream SCR/NOx outlet temperature to upstream DPF temperature (if available) during idle and a controlled regeneration
Check for additional related codes (DPF, NOx sensor, injector, turbocharger, EGR)
Review service information/TSBs for sensor calibration or software updates relevant to high-temp detection

Signal parameters

Sensor type: typically thermistor or thermocouple (check OEM spec)
Typical idle/normal exhaust range: ~200–450 °C (varies by engine)
Expected regeneration range: ~500–700 °C (varies by engine and strategy)
Critical/trigger range: over ~800–900 °C may flag overtemperature (manufacturer-dependent)
Sensor electrical: voltage outputs typically 0.2–4.5 V or millivolt thermocouple output; resistance of NTC decreases with rising temperature (refer to OEM chart)

Diagnostic algorithm

Capture codes and freeze frame; note engine load, vehicle speed, and coolant temp at fault
Visually inspect sensor and harness; repair any damaged wiring or connectors before further testing
With connector disconnected, measure sensor resistance or thermocouple voltage at ambient and while applying controlled heat (heat gun) and compare to OEM specification to verify sensor response
Backprobe sensor signal with scan tool during a controlled regen or simulated heating to verify real-time temperature trace and compare upstream/downstream sensors
If sensor reading is erratic or out-of-range but wiring and connector are good, replace the temperature sensor and retest
If sensor and wiring test good, inspect DPF regeneration strategy: check injectors, fuel dosing, turbocharger/EGR operation for causes of excessive exhaust temperature
After repairs, clear codes and perform a road/regen test while monitoring temperatures to confirm fault does not return

Likely causes

Faulty SCR/NOx catalyst outlet temperature sensor or connector
Wiring short to voltage/ground or broken conductor to sensor
Sensor thermocouple/thermistor contaminated or damaged by soot/oil
DPF regeneration strategy producing excessive temperature (fuel dosing, injector timing)
Sensor mounting/seal missing or sensor pushed into hot gas flow causing false high reading

Fault status

⚠️ Status

P214D — SCR NOx catalyst outlet temperature exceeded allowed threshold during particulate filter (DPF) regeneration; ECM logged overtemperature condition.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours