P1143 NISSAN Possible Causes
- Faulty heated oxygen sensor, bank 1
- Intake air leaks
- Open or short circuit in the bank 1 heated oxygen sensor harness
- Poor electrical connection in the heated oxygen sensor circuit, bank 1
- Fuel pressure
- Injectors
How to Fix Code P1143 NISSAN?
Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.
Technical Notes
If there is no intake air leak, the most likely cause of code P1143 is the front O2 sensor bank 1.
When is the Code Detected?
The maximum and minimum sensor voltages are not reached at the specified voltages.
Possible Symptoms
- Engine light on (or engine service warning light soon)
P1143 NISSAN Meaning
The heated oxygen sensor 1 is placed in the front tube. It detects the amount of oxygen in the exhaust gases compared to the outside air. The heated oxygen sensor 1 has a closed-end zirconia ceramic tube. Zirconia generates a voltage of about 1 V under richer conditions to 0 V under leaner conditions. The heated oxygen sensor 1 signal is sent to the engine control module (ECM). The ECM adjusts the injection pulse duration to achieve the ideal air-fuel ratio. The ideal air-fuel ratio occurs near the sharp change from 1V to 0V.