P1276 Possible Causes
- Faulty air/fuel ratio (A/F) sensor 1, bank 1
- Air-fuel ratio (A/F) harness is open or shorted
- Poor electrical connection in the air-fuel ratio (A/F) circuit
How is code P1276 repaired?
Start by checking the “Possible Causes” listed above. Visually inspect the wiring harness and associated connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
Possible Symptoms
- Engine light on (or service engine soon warning light)
P1276 Meaning
The A/F sensor is a planar dual-cell limit current sensor. The sensor element of the A/F sensor combines a Nernst concentration cell (sensor cell) with an oxygen pump cell, which transports ions. It contains a heating element within the component.
The sensor can accurately measure λ=1, as well as in both lean and rich ranges. With its control electronics, the sensor provides a clear and continuous signal across a wide λ range (0.7 < λ < air).
Exhaust gas components diffuse through the diffusion gap at the oxygen pump electrode and the Nernst concentration cell, where they are brought to thermodynamic equilibrium.
An electronic circuit controls the pump current through the oxygen pump cell so that the exhaust gas composition in the diffusion gap remains constant at λ=1. Therefore, the A/F sensor can indicate the air/fuel ratio through this pumping current. Additionally, a heating element is integrated into the sensor to maintain the required operating temperature of 700 to 800°C (1,292 to 1,472°F).