Code
P1414
CITROEN
P — Powertrain
Catalytic converter upstream temperature sensor short circuit to positive or open circuit
Views:
UK: 1
EN: 4
RU: 3
AI status
Completed
Completed
100%
Causes
- Damaged sensor (internal short or open)
- Broken, pinched or chafed wiring harness to the sensor
- Corroded or loose connector pins causing open/short to B+
- Short circuit to battery positive caused by nearby wiring contact
- Failed sensor heater element
- Poor ground or ECU connector fault
Symptoms
- Malfunction Indicator Lamp (MIL) / Check Engine Light illuminated
- Possible failed emissions test or stored readiness/monitor fault
- Engine may run normally but emissions control functions degraded
- Reduced catalyst monitoring (delayed diagnosis of catalyst efficiency)
- Possible limp-home behavior if ECU limits functions (manufacturer-dependent)
What to check
- Read and record freeze-frame and live data with an OBD scanner supporting manufacturer PIDs
- Visual inspection of sensor wiring, connector and harness routing near exhaust and catalytic converter
- Check for water, corrosion, melted insulation or pin damage at the connector
- Measure continuity and resistance between sensor terminals and ECM connector with ignition off
- Back-probe the sensor connector (key on) to verify heater supply voltage and sensor signal levels
- Compare measured values to expected parameters and wiring diagrams for the specific vehicle
Signal parameters
- Heater supply voltage (key ON, heater commanded) ≈ battery voltage (near 12 V) when relay/ECU supplies heater — if shorted to positive reading may be stuck at B+
- Heater resistance (cold, typical range) ≈ low ohms (commonly 1–50 Ω depending on design) — open circuit = infinite resistance
- Thermistor/sensor element resistance at ~20 °C typically in the kilo-ohm range for NTC-type sensors (varies by sensor) — resistance should change with temperature (decrease as temperature rises)
- Signal voltage to ECU usually 0–5 V (model-dependent) — open circuit may show no voltage change, short-to-positive may show stuck-high voltage
Diagnostic algorithm
- Retrieve freeze-frame data and confirm P1414 is current/pending and note related codes.
- Perform a careful visual inspection of the upstream catalytic converter temperature sensor, connector and harness routing for heat damage, chafing, melted insulation or corrosion.
- With ignition OFF disconnect the sensor harness; measure resistance between sensor signal/heater pins and vehicle battery positive and chassis ground to detect unwanted shorts or opens.
- Measure sensor heater resistance at the sensor connector (compare to factory spec). If infinite or out-of-range, suspect open/faulty heater.
- With key ON (engine OFF) back-probe harness to check heater supply voltage and sensor signal. If the sensor signal or heater feed is at battery voltage with no command, check for short to positive in harness or ECU driver fault.
- Remove sensor (if needed) and measure thermistor resistance at ambient. Warm sensor gently (hot air) and verify resistance decreases/increases per spec to confirm thermistor action.
- Check continuity between sensor connector and ECM pins to confirm no open circuit; wiggle harness to detect intermittent faults.
- If wiring and connectors OK but sensor out-of-spec, replace the upstream catalytic temperature sensor. If wiring is shorted, repair/replace harness and connectors and protect against heat/contact points.
- After repair, clear codes, perform readiness/freeze-frame clear, and road-test to confirm the code does not return and related monitors run.
- If problems persist after sensor and wiring verified, consult manufacturer wiring diagrams and test ECM outputs/grounds or replace ECU per service procedures.
Likely causes
- Wiring harness damaged by heat/chafing near exhaust/catalyst
- Connector corrosion or pin pushed out making intermittent contact
- Failed upstream catalyst temperature sensor (NTC or integrated heater)
- Short from harness to 12 V (contact with battery feed or relay wiring)
Fault status
Status
Upstream catalytic-converter temperature sensor circuit indicates open or short to positive (heater or signal circuit).
Repair difficulty: Medium
Diagnostic time: 1.0 - 2.5 hours
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