What does it mean?
P1117 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: O2 Control (Bank 1 Sensor 2) Open .
Symptoms
- Check engine light on with the catalyst efficiency monitor unable to run
- Readiness monitors staying incomplete, so the vehicle cannot pass an emissions test
- Downstream sensor voltage in live data flat and unresponsive
- Slight change in fuel consumption where the rear sensor trims the mixture
- Engine usually drives normally, which is why the fault often surprises the owner
- Fault frequently found after exhaust or suspension work
Likely causes
- Broken or corroded signal wire in the section that runs along the underbody
- Connector unplugged, unlatched or with a terminal that has backed out of its housing
- Sensor element open internally after long service or thermal shock
- Wiring damaged by road debris, corrosion or rodents under the vehicle
- Harness burnt where it has rested against the exhaust pipe
- Missing sensor ground, on designs that use a separate ground wire
- Module input circuit fault, only after the harness and sensor are proven
How to fix it
- Look at the downstream sensor voltage in live data; a flat line with no activity supports an open circuit
- Inspect the sensor connector under the vehicle for corrosion, a pushed-back terminal and a broken latch
- Check continuity of the signal and ground wires from the connector back to the module pin
- Measure the sensor across its signal terminals; an infinite reading condemns the sensor
- Follow the harness along the exhaust and floor pan for burnt, broken or chewed sections
- Repair the wiring with a proper sealed joint, since this area is exposed to water and salt
- Fit a new sensor if it tests open, then confirm the signal responds after the exhaust warms up