P1272 Possible Causes
- Faulty Air/Fuel Ratio (A/F) Sensor 1, Bank 1
- Air/Fuel Ratio (A/F) Sensor 1 Bank 1 harness is open or shorted
- Air/Fuel Ratio (A/F) Sensor 1 Bank 1 circuit poor electrical connection
How is code P1272 repaired?
Start by checking the “Possible Causes” listed above. Visually inspect the related wiring harness and 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)
P1272 Meaning
The A/F sensor is a planar dual-cell limit current sensor. The A/F sensor’s sensing element is the combination of a Nernst concentration cell (sensor cell) with an oxygen pump cell, which transports ions. It has a heating element in the component.
The sensor is capable of accurately measuring λ=1, but also in the lean and rich ranges. With its control electronics, the sensor emits a clear and continuous signal over a wide λ range (0.7 < λ < air).
The 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 composition of the exhaust gases in the diffusion gap remains constant at =1. Therefore, the A/F sensor is capable of indicating the air/fuel ratio by this pumping current. Additionally, a heating element is built into the sensor to ensure the required operating temperature of 700 to 800°C (1,292 to 1,472°F).