Code
P1414
PEUGEOT
P — Powertrain
Catalytic converter upstream temperature sensor short circuit to positive or open circuit
AI status
Completed
Completed
100%
Causes
- Open circuit (broken wire) in sensor signal or heater circuit
- Short to battery positive in signal or heater wiring
- Corroded/poor connector at the sensor
- Failed upstream catalytic converter temperature sensor (thermistor or internal heater)
- Connector pushed out or pin damage
- Poor ground or power supply to sensor
Symptoms
- Malfunction Indicator Lamp (MIL) / Check Engine Light ON
- Possible poor emissions / failed emissions test
- Reduced driveability or limp mode in some vehicles (rare)
- Stored freeze-frame data with abnormal catalyst temperature readings
- Possible rough idle if ECM uses sensor for fuel/ignition adjustments
What to check
- Read and record freeze-frame and live data for pre-cat temperature sensor and related sensors (MAF, O2, coolant temp)
- Visual inspection of sensor, connector, and wiring harness for heat damage, chaffing, or corrosion
- Backprobe sensor connector and observe signal voltage with ignition on and engine running
- Measure resistance of the temperature sensor with connector disconnected and compare to manufacturer spec
- Check for 12V supply (if sensor has heater) and good ground at the connector
- Wiggle wiring while monitoring live data to reproduce intermittent faults
Signal parameters
- Sensor type: typically NTC thermistor (resistance decreases as temperature rises); specifics vary by model
- Typical signal range: ~0.1–5.0 V (varies by design). Open circuit or short to positive often shows near battery voltage or a flagged out-of-range value
- Open-circuit symptom: very high resistance (OL) at room temp or signal >4.5–5 V
- Short-to-positive symptom: signal near battery voltage (~12 V) or ECU detects over-voltage
- Short-to-ground symptom (not the code text but useful): signal ~0 V
- Heater circuit (if present): supply usually battery voltage with a low-ohm heater to ground; check current draw per spec
Diagnostic algorithm
- Connect a scan tool and confirm P1414 and any related codes. Record freeze-frame and live pre-cat temp values.
- Visual inspection: inspect sensor body, connector, and harness for heat damage, melted insulation, corrosion, or disconnection. Repair obvious damage.
- With ignition off, disconnect the sensor connector. Measure resistance between the temperature sensor terminals (thermistor) and compare to factory specification or expected NTC behaviour (resistance falls as sensor warmed). An open reading indicates a failed sensor or broken wire.
- Check supply circuits: with connector connected and ignition ON (engine off), backprobe the supply and ground pins. Verify battery voltage on heater supply (if equipped) and good ground. Absence indicates wiring/connector issue or blown fuse.
- Backprobe the signal pin with ignition ON and engine cold, then warm engine while watching live data. Look for plausible temperature changes. If signal reads near battery voltage or does not change, suspect short to positive or open.
- Check for short to battery: with ignition OFF, measure continuity between the signal wire and battery positive. If low resistance, repair wiring short.
- Check for open circuit: measure continuity between sensor signal pin and ECU input pin. Open indicates broken wire or connector. Repair as needed.
- Wiggle test wiring while monitoring live data to find intermittent faults and locate damage.
- If wiring and connector test good and sensor out of spec, replace the upstream catalytic temperature sensor and clear codes.
- If fault returns after replacement and wiring checks OK, consider ECU input/ground driver testing or replacement by qualified technician.
Likely causes
- Damaged harness insulation near exhaust or mounting bracket causing short to chassis or positive
- Connector contamination/corrosion causing intermittent/high resistance or open
- Sensor overheated/failed from exhaust leak or contact with hot components
- Broken solder joint or pin inside sensor connector
- Disconnected connector after recent work
Fault status
Status
Upstream catalytic converter temperature sensor circuit: short to positive or open. Monitor sensor voltage/resistance and inspect wiring/connectors.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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