Code
P1141
HUMMER
P — Powertrain
Heated Oxygen Sensor (HO2S) Heater Control Circuit Bank 1 Sensor 2
Views:
UK: 23
EN: 28
RU: 24
AI status
Completed
Completed
100%
Causes
- Blown fuse or failed heater relay for O2 sensor heater circuit
- Open or high-resistance wiring between PCM and sensor heater
- Short to ground or short to voltage in heater wiring or connector
- Corroded, damaged or water-intruded sensor connector
- Failed HO2S heater element (internal open or high resistance)
- PCM/ECU heater driver fault or internal short
Symptoms
- Malfunction Indicator Lamp (MIL/CEL) illuminated
- Possible failed emissions test or catalytic monitor disable
- Reduced ability to run catalyst readiness tests (downstream sensor heater required)
- Usually no major drivability symptoms, but can cause stored codes and emissions issues
- Occasional rough idle or decreased fuel economy if related faults affect feedback
What to check
- Read and record freeze frame and related codes; check for other O2 sensor or heater codes
- Visually inspect wiring and connector at bank 1 sensor 2 for corrosion, heat damage or water intrusion
- Check heater fuse(s) and related relays for continuity and operation
- Backprobe heater connector and verify battery voltage on heater supply pin with key ON (if circuit is power‑switched)
- With PCM commanding heater ON, check for switching voltage or ground at the control pin (backprobe while commanding)
- Measure heater element resistance at the sensor (unplug harness)
Signal parameters
- Typical heater supply voltage: ~12 V (battery voltage) present at heater power feed with key ON (design dependent)
- PCM control: either grounds the heater circuit or supplies switched voltage; when commanded ON expect switching to battery or ground depending on design
- Typical heater element resistance (downstream oxygen sensor): commonly ~2–20 ohms (most narrowband sensors 3–15 Ω) — consult vehicle-specific spec
- Heater current when ON: typically 0.3–2.0 A depending on resistance and supply voltage
- If commanded OFF: control pin should be near supply or high-impedance depending on the design (no continuous current)
Diagnostic algorithm
- Connect a scan tool, read and record DTCs and freeze frame; clear codes and attempt to re-run to confirm P1141 returns.
- Visually inspect sensor 2 (bank 1) harness and connector for corrosion, bent pins, heat damage, or water entry; repair as needed.
- Check related fuses and relays for the O2 heater circuit; replace any blown fuse and test operation.
- With connector unplugged, measure heater element resistance across the heater pins of the sensor. Compare to vehicle spec. If open or out of range, replace sensor.
- Reconnect harness. With key ON (engine OFF) backprobe the heater power feed — verify battery voltage present if circuit uses fused power. If no voltage, trace fuse/relay/power feed.
- Command the heater ON via scan tool (if capable) and backprobe the control wire. Verify the PCM is switching (grounding or applying voltage) as specified. If PCM does not command, check inputs and PCM grounds.
- Check for shorts to ground or battery on the control wire (with ignition OFF). Repair wiring insulation faults as needed.
- If wiring and power/ground are good but heater still fails, replace the downstream HO2S (Bank 1 Sensor 2) with correct OEM or equivalent sensor.
- After repair, clear codes and perform drive cycle or readiness test to verify the code does not return.
- If fault persists despite good sensor and wiring, consider PCM/ECU driver fault and consult manufacturer diagnostics or replace PCM only after thorough verification.
Likely causes
- Open or corroded connector at bank 1 sensor 2
- Broken or chafed heater wiring (open/high resistance) between sensor and fuse/PCM
- Failed heater element in the downstream O2 sensor
- Blown fuse or failed heater relay supplying sensor heater
- PCM/ECU driver failure (less common)
Fault status
Status
Heater circuit fault detected for Bank 1, Sensor 2 oxygen sensor (heater open/short/high resistance or control circuit failure).
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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