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Home / DTC / P1107 — Heating of HO2S 2 ahead of TWC

P1107 — Heating of HO2S 2 ahead of TWC

Detailed page for trouble code P1107.

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22,491specific
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Code

P1107

PORSCHE P — Powertrain

Heating of HO2S 2 ahead of TWC

Brand: PORSCHE
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Failed HO2S heater element (internal open or short)
  • Damaged, corroded or disconnected sensor connector
  • Short to battery or short to ground in heater power/ground wiring
  • Faulty fuse or relay supplying heater power
  • Poor chassis/engine ground or high resistance in ground circuit
  • ECM/PCM driver failure or internal short

Symptoms

  • Malfunction Indicator Lamp (MIL) / Check Engine Light illuminated
  • Possible rich/lean running or rough idle if closed‑loop is affected
  • Reduced fuel economy or increased emissions
  • Failed emissions test
  • Possible battery drain if heater remains powered while engine off (rare)
  • Intermittent MIL if wiring/connector is intermittent

What to check

  • Read stored freeze frame and pending codes with a scan tool; record engine conditions
  • Verify P1107 is current and note any related O2 or heater codes
  • Visually inspect sensor, connector and wiring harness for damage, corrosion, heat damage or melting
  • Check fuses/relays that supply O2 sensor heaters
  • Backprobe sensor connector with key ON and engine OFF to check heater supply voltage and ground presence
  • Command the heater ON/OFF with a capable scan tool and observe behavior/current draw if supported

Signal parameters

  • Heater supply voltage (key ON) — typically battery voltage (~12V) on the power feed; verify presence and that it switches via ECM or relay
  • Heater control signal/ground from ECM — may be switched ground or PWM; verify switching when commanded
  • Heater element resistance (sensor unplugged) — consult manufacturer spec; typical heated O2 sensors often measure low ohms (commonly 2–20 Ω depending on sensor). Use OEM spec for exact value
  • Current draw when heater energized — excessive current indicates short; very low or open circuit indicates open heater
  • Continuity/resistance to ground for ground circuit; voltage drop across ground under load

Diagnostic algorithm

  1. Retrieve and record P1107 and any related codes; clear codes and run functional test to re‑confirm.
  2. Visually inspect sensor 2 upstream area, harness and connector for damage, corrosion, heat, or fluid contamination.
  3. Check related fuses/relays for the O2 heater circuit; replace if blown and recheck.
  4. With ignition ON (engine OFF), backprobe the heater power terminal — verify battery voltage present if it should be powered; if no voltage, trace fuse/relay/wiring to source.
  5. With ignition ON, command heater ON using a scan tool (if supported) and observe supply/ground switching and current draw. If no change, suspect wiring or ECM driver.
  6. Disconnect sensor and measure heater resistance (ohms) across heater terminals. Compare to OEM spec. Open or very high resistance = bad sensor; near zero or very low could indicate short.
  7. Check for short to battery: with ignition OFF measure for battery voltage present on circuits that should be off. Check for short to ground: measure continuity from heater positive to ground if abnormal.
  8. Repair/replace damaged wiring, connector or sensor as indicated. After repair, clear codes and perform drive cycle and OBD readiness tests.
  9. If wiring and sensor test good, suspect ECM heater driver failure and consult manufacturer service information before replacing ECM (confirm with bench tests or professional diagnosis).

Likely causes

  • Open or high resistance in heater ground or supply circuit
  • Shorted heater element drawing excessive current
  • Corroded/loose connector at the sensor
  • Failed heater fuse or relay
  • Faulty ECM heater driver

Fault status

⚠️ Status
Heater circuit malfunction for HO2S 2 (upstream of TWC). Heater is open, shorted, drawing abnormal current, or heater control circuit is faulty.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

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136

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