P1169 — HO2S11 Label Circuit High Voltage Fault Bank 1 Sensor 1

Causes

• Damaged or contaminated upstream O2 sensor (Bank 1 Sensor 1)
• Signal wire shorted to battery/ignition voltage
• Poor or corroded connector or ground on the sensor circuit
• Faulty sensor heater (open/short) or heater power short
• Rich running condition (excess fuel) causing persistently high O2 voltage
• ECM internal fault or poor reference ground

Symptoms

• Check Engine Light (MIL) illuminated
• Poor fuel economy and possible rich smell or black exhaust smoke
• Engine may run rough at idle or during acceleration
• Failed emissions test (high HC/CO)
• Possible reduced drivability until condition is corrected

What to check

• Read and record freeze frame and live data (HO2S11 voltage, heater status, short-term/long-term fuel trims, MAF/MAP readings)
• Compare upstream O2 signal to expected narrow-band behavior (rapid switching between ~0.1–0.9 V) and to Bank 2 sensor if present
• Visually inspect sensor connector and harness for damage, corrosion, pin push-out, melted insulation or rodent damage
• Backprobe HO2S signal wire with engine running to check for constant high voltage or voltage spikes
• Check for short to battery on signal wire (measure continuity to 12V with ignition ON) and short to ground
• Measure sensor heater resistance and check for battery voltage at heater power feed when ECM commands heater on

Signal parameters

• Expected HO2S signal (narrowband): ~0.1 V (lean) to ~0.9 V (rich), switching multiple times per second at closed-loop idle
• A sustained high reading near supply (e.g., >0.8–0.9 V) may trigger the DTC
• Heater supply: battery/ignition voltage present at heater feed when heater commanded on; heater resistance typically low (manufacturer-specific; often single to tens of ohms)
• ECM grounds and reference voltages should be stable (no more than a few millivolts of noise on sensor ground)

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