Possible causes

– Faulty Rear Heated Oxygen Sensor Bank 2
– Rear Heated Oxygen Sensor Bank 2 harness is open or shorted
– Rear Heated Oxygen Sensor Bank 2 circuit poor electrical connection
– Inappropriate fuel pressure
– Faulty fuel injectors
– Intake air leaks may be faulty
– Exhaust gas leaks

Tech notes

Replacing the Rear Heated Oxygen Sensor Bank 2 usually takes care of the problem.

When is the code detected?

The P0157 code is set when the Engine Control Module (ECM) detects that the rear O2 sensor signal voltage remains excessively low for an extended period of time.

Symptoms

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

P0157 Description

The heated oxygen sensor 2 (HO2S), after three way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. For optimum catalyst operation, the air fuel mixture (air-fuel ratio) must be maintained near the ideal stoichiometric ratio. The HO2S output voltage changes suddenly in the vicinity of the stoichiometric ratio. The Engine Control Module (ECM) adjusts the fuel injection time so that the air-fuel ratio is nearly stoichiometric. The HO2S generates a voltage between 0.1 and 0.9 V in response to oxygen in the exhaust gas. If the oxygen in the exhaust gas increases, the air-fuel ratio becomes Lean. The ECM interprets Lean when the HO2S voltage is below 0.45 V. If the oxygen in the exhaust gas decreases, the air-fuel ratio becomes Rich. The ECM interprets Rich when the HO2S voltage is above 0.45 V.

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P0157 Information for specific makes

P0157 INFINITI
P0157 NISSAN
P0157 BUICK
P0157 HONDA
P0157 ACURA
P0157 BMW
P0157 CHRYSLER
P0157 DODGE
P0157 JEEP
P0157 HYUNDAI
P0157 KIA
P0157 LEXUS
P0157 TOYOTA
P0157 SCION
P0157 MAZDA
P0157 MITSUBISHI
P0157 SUBARU
P0157 AUDI
P0157 VOLKSWAGEN
P0157 JAGUAR
P0157 CADILLAC
P0157 CHEVROLET
P0157 GMC
P0157 PONTIAC
P0157 SATURN