Possible causes

– Air/Fuel Ratio Sensor Bank 1 harness is open or shorted
– Air/Fuel Ratio Sensor Bank 1 circuit poor electrical connection
– Faulty Air/Fuel Ratio Sensor Bank 1
– Inappropriate fuel pressure
– Faulty fuel injectors
– Intake air leaks may be faulty
– Exhaust gas leaks

Tech notes

For the following Acura models to fix this problem, check the sensor wiring and connections for damage. If the sensor circuit is OK, and the DTC(s) come back after clearing them and doing a short test-drive, replace the A/F sensor. The replacement A/F sensors in Honda parts stock are an improved version over the original sensor.

When is the code detected?

If the IPB 1 terminal voltage is out of a specified range, the PCM detects a malfunction and stores a DTC.

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)
– High Fuel Consumption
– Excessive Smoke from Exhaust

P2237 ACURA Description

The rear air/fuel ratio (A/F) sensor (bank 1, sensor 1) is installed in the exhaust manifold and detects oxygen content in the exhaust gas. The rear A/F sensor transmits output voltage to the powertrain control module (PCM). The PCM controls fuel injection duration by comparing the target air/fuel ratio with the rear A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control.