Code
P1414
DS
P — Powertrain
Catalytic converter upstream temperature sensor short circuit to positive or open circuit
AI status
Completed
Completed
100%
Causes
- Open or broken wiring in the sensor harness
- Connector corrosion, bent pins or poor connection
- Sensor internal failure (open circuit or short)
- Short to battery positive (damaged insulation, chafing)
- Blown fuse or power supply fault feeding the sensor heater (if fitted)
- Control module (ECM/PCM) fault or damaged sensor driver
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- Stored P1414 (and possibly related) codes
- Possible failed emissions test (catalyst monitoring disabled)
- Erratic or implausible exhaust temperature readings in live data
- Reduced closed-loop catalyst diagnostics; potential drivability or warm‑up performance effects (rare)
What to check
- Read and record freeze frame and all stored codes; clear codes and reproduce if safe
- Scan tool: monitor upstream catalyst temperature PID and heater status while key ON and during warm-up
- Visually inspect sensor connector and wiring along the harness for chafing, heat damage, corrosion and pin condition
- Check related fuses and power supplies for the heater circuit (if applicable)
- Compare upstream and downstream catalyst temperature sensors (live data) for plausibility
Signal parameters
- Temperature sensor: thermistor-type signal — resistance changes with exhaust temperature (NTC: resistance falls as temp rises)
- Signal line: low-voltage analog to ECM (varies with temp); expected gradual change with exhaust heating
- Heater circuit (if present): switched 12 V supply from ECM or fused battery feed; heater current when commanded by ECM
- Fault types: open-circuit (infinite resistance/no signal) or short-to-positive (sensor output near battery voltage)
Diagnostic algorithm
- Obtain freeze frame data and note operating conditions when code set
- Inspect sensor and wiring visually: connectors, clips, harness routing near exhaust and catalytic converter for heat damage
- With ignition OFF disconnect sensor and inspect pins for corrosion, bent pins or presence of voltage on signal/heater pins
- Using wiring diagram, identify pins: back-probe with DVOM/oscilloscope. With key ON (engine OFF) measure: supply/heater feed for 12 V presence (if heater circuit present); signal reference and ground continuity to ECM
- Measure sensor resistance at ambient (cold) between signal and reference/ground pins and compare to manufacturer spec (if available). If open/infinite or short to battery present, replace sensor
- If resistance OK, with ECM commanding heater ON, check for proper voltage/current on heater circuit and no short to positive
- Wiggle-test harness while watching live data to reproduce intermittent faults
- If wiring, connector and sensor pass tests, perform ECM pin/ground checks. If ECM outputs are shorted or stuck high, suspect module fault and test/replace as directed by manufacturer procedures
- After repairs, clear codes and perform drive cycle to confirm correct operation and that code does not return
Likely causes
- Damaged/abraded wire contacting battery voltage or hot circuit
- Disconnected or corroded connector at the upstream catalyst temp sensor
- Failed temperature sensor element (open/short)
- Failed sensor heater supply or fuse causing abnormal circuit readings
- Aftermarket work or repairs disturbed wiring harness near exhaust/catalyst
Fault status
Status
Upstream catalytic converter temperature sensor circuit shorted to battery positive or open; ECM detects implausible or missing temperature signal.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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