When you have multiple codes related to several different emissions components, you have to use your diagnostic skills to determine the actual cause. Follow this Real Fix to see how a Chevrolet Cruze with multiple emissions codes was diagnosed and which component caused the problem.
2016 Chevrolet Cruze Limited LT 1.4L
P0106, P015B, P0171, P1101, Replaced Valve Cover
The customer states the check engine light is on.
Connected a scan tool and found codes: P0106 – Manifold Absolute Pressure (MAP) Sensor Performance; P015B – O2 Sensor Delayed Response – Lean to Rich (Bank 1 Sensor 1); P0171 – System Too Lean (Bank 1) and P1101 – Intake Air Flow System Performance. With the scan tool connected, cleared the codes, performed a road test, monitored the live data and found the long term and short term fuel trim was out of specifications. Performed a visual inspection of the air intake system and found no apparent faults. Connected a smoke machine to the air intake system, induced smoke into the system and found the smoke machine indicated a leak in the system. Removed the engine oil fill cap and found smoke leaked from the valve cover. Removed the valve cover for inspection and found the positive crankcase ventilation (PCV) valve was damaged. The PCV valve is integrated into the valve cover and is replaced as an entire unit. These test results verified the valve cover was faulty.
Replaced the valve cover, cleared codes, performed a road test and verified the vehicle operated properly. The check engine light did not illuminate and no fault codes returned.
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