Symptoms

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

Possible Causes

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

When Detected

The P0158 code is set when the Engine Control Module (ECM) detects that the rear O2 sensor signal voltage remains excessively high for an extended period of time.

Tech Notes

Replacing the rear O2 Sensor bank 2 usually takes care of the problem.

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.

Information For Specific Makes

P0158 ACURA P0158 HONDA P0158 BMW P0158 CHRYSLER P0158 DODGE P0158 JEEP P0158 FORD P0158 HYUNDAI P0158 INFINITI P0158 NISSAN P0158 KIA P0158 LEXUS P0158 SCION P0158 TOYOTA P0158 MAZDA P0158 MITSUBISHI P0158 SUBARU P0158 AUDI P0158 VOLKSWAGEN P0158 JAGUAR