Code
P1482
PONTIAC
P — Powertrain
Catalyst Temperature Sensor Circuit Shorted Low
Views:
UK: 34
EN: 80
RU: 54
AI status
Completed
Completed
100%
Causes
- Shorted wiring to ground in catalyst temperature sensor circuit
- Damaged or shorted catalyst temperature sensor (thermistor)
- Corroded, loose, or damaged connector/pins at sensor or PCM
- PCM input or ground fault (rare)
- Exhaust damage/physical sensor damage from heat or impact
Symptoms
- Check Engine Light (MIL) illuminated
- Stored P1482 trouble code (Catalyst Temp Sensor Circuit Shorted Low)
- Failed emissions test or poor catalyst performance status
- Possible limp/limited mode or degraded engine performance in some vehicles
- No or abnormally low catalyst temperature reading on live data/scan tool
What to check
- Retrieve trouble code and freeze-frame data with a scan tool; record PID values for catalyst temperature and related sensors
- Visually inspect sensor, wiring harness and connector near catalytic converter for heat damage, chafing, corrosion or cuts
- Backprobe the sensor connector and monitor voltage and resistance while engine is cold and warming up
- Check for continuity to PCM and for unintended continuity to chassis ground (short to ground)
- Inspect PCM connector pins for corrosion or damage and check PCM grounds and power feeds
- Perform a wiggle test of harness while monitoring live data to detect intermittent shorts
Signal parameters
- Sensor type: typically a thermistor (NTC or similar) — resistance decreases as temperature increases
- Expected signal range: sensor circuits generally operate within a 0–5 V range; a shorted-low condition often reads near 0 V (or close to ground) on the signal line
- At ambient temperature the thermistor resistance is commonly in the kilo-ohm range and will fall as exhaust/catalyst heats (specific resistance varies by sensor)
- PCM reference: sensor may use a PCM-supplied reference or be read as a direct resistance; check vehicle-specific service data for exact values
Diagnostic algorithm
- Connect a professional scan tool and confirm P1482; record freeze-frame and live PID for catalyst temperature and related sensors
- With engine off and cooled, visually inspect sensor, harness and connector for heat damage, melted insulation, pin corrosion or physical damage. Repair obvious damage.
- Backprobe the sensor signal and reference/ground pins. With ignition on, verify the PCM reference voltage (if used) and the signal voltage. Note: shorted-low will show signal near 0 V.
- Check continuity between the sensor signal wire and chassis ground. If there is continuity with low resistance, locate and repair the short.
- Measure sensor resistance at the connector (unplugged). Compare behavior to ambient vs warmed states if safe to heat the sensor (do not exceed safety limits). Resistance should decrease as temperature rises; a near-zero resistance at ambient suggests a shorted sensor.
- If wiring and sensor check good, trace continuity from sensor connector to PCM. Inspect PCM connector pins for shorts or bent pins. Repair any wiring faults or connector issues.
- If repairs are made, clear codes, perform a controlled warm-up/road test and re-scan. If P1482 returns, replace the catalyst temperature sensor. If it still returns after sensor replacement and wiring checks, consider PCM diagnosis by a specialist.
- Always exercise caution near the exhaust system — components can be extremely hot. Disconnect battery if performing connector repairs where recommended by manufacturer.
Likely causes
- Damaged sensor element or water/contaminant ingress causing low resistance
- Chafed or pinched harness shorting to chassis ground near exhaust area
- Corroded connector causing low-resistance path or incorrect reference connection
- Shorted sensor heater (if equipped) or internal sensor wiring failure
- PCM connector pin shorted or internal PCM fault (least likely)
Fault status
Status
P1482 — Catalyst Temperature Sensor Circuit Shorted Low: PCM detects a lower-than-expected voltage/resistance on the catalyst temperature sensor circuit (possible short to ground or sensor/wiring failure). Inspect sensor, harness, connectors, and PCM inputs.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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