Code
P1119
PORSCHE
P — Powertrain
Heating of HO2S 2 ahead of TWC
Views:
UK: 6
EN: 7
RU: 7
AI status
Completed
Completed
100%
Causes
- Failed HO2S heater element (sensor internal open or short)
- Broken/corroded wiring or connector to the sensor heater
- Blown fuse or faulty relay supplying heater circuit
- High-resistance connection (corrosion, damaged pin)
- Short to battery or ground in heater circuit
- Defective ECU heater driver output
Symptoms
- MIL (Check Engine) lamp illuminated
- Possible poor cold-start emissions and longer catalyst light-off time
- Erratic O2 sensor warm-up behavior or delayed switching
- Reduced fuel economy or temporary rough idle until sensor warms
- Possible persistent fault after repair if underlying wiring/ECU not fixed
What to check
- Read freeze-frame and live data with a scan tool; confirm P1119 and related codes
- Visual inspection of HO2S #2 connector and wiring for damage, corrosion, heat or oil contamination
- Check relevant fuses and relays for the heater circuit
- Backprobe sensor connector: measure supply voltage with key ON and heater control/pulse while cranking or running
- Measure heater resistance at the sensor (with sensor disconnected)
- Check continuity and shorts between sensor heater pins and ECU/power/ground
Signal parameters
- Heater supply voltage (key ON): approx. battery voltage ~11–14 V at the fuse/supply pin
- Heater element resistance (typical range): roughly 2–20 ohms (manufacturer-specific — consult Porsche spec)
- Heater current when energized: commonly in the 0.5–2 A range (varies by sensor)
- ECU often switches the heater on/off or grounds the circuit (PWM) — control signal may be pulsed rather than steady ground
- Expected warm-up time: heater should reach operating temperature rapidly (seconds) — fault set if not meeting ECU profile
Diagnostic algorithm
- Verify code and related stored data with a scan tool; record freeze-frame and any other O2/heater codes.
- Perform a visual inspection of sensor #2 (upstream) connector and harness for corrosion, melted insulation, chaffing or disconnection.
- Check fuses/relays that feed the O2 heater circuit; replace any blown fuses and retest.
- With ignition ON (engine off), backprobe the sensor connector: verify battery voltage at the heater supply pin. If no supply, trace to fuse/relay/power source.
- With key OFF, disconnect sensor and measure heater resistance across heater pins. Compare to specification. Open or extremely high resistance = replace sensor.
- With ignition ON and engine running or cranking, backprobe control pin to confirm ECU is pulsing/grounding the heater circuit. Use an oscilloscope or lab scope if available to view PWM.
- Check continuity from sensor connector to ECU and for shorts to battery or chassis ground. Repair any damaged wiring or connectors.
- If wiring and supply are good but a replacement OEM sensor also fails, suspect ECU driver fault — consult dealer-level diagnostics or replace ECU only after exhaustive wiring/sensor verification.
- After repairs, clear codes and perform a drive cycle to confirm the fault does not return.
Likely causes
- Open heater element inside the upstream oxygen sensor (most common)
- Connector corrosion or water intrusion at sensor plug
- Missing/failed fuse or relay feeding sensor heater
- Damaged wiring harness (abrasion, heat damage) between sensor and ECU
- Intermittent connector contact causing heater failure
Fault status
Status
Heater circuit for upstream oxygen sensor (HO2S) #2 is not functioning within the expected parameters (open, short, excessive resistance, or insufficient current). The ECU has stored P1119 and may illuminate the MIL. Further testing required to determine whether the sensor, wiring, fuse/relay, or ECU driver is at fault.
Repair difficulty: Medium
Diagnostic time: 0.5-2 hours
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