Exhaust Leaks Hit Chevy Vehicles
This bulletin applies to 2010-2015 Chevy Camaro, 2015-2016 Colorado equipped with a 3.6L engine, and 2008-2017 Equinox vehicles equipped with a 3.0L or 3.6L engine.
The SES light may be on, accompanied by DTC P2097 or P2099.
According to Chevy, the most common concerns have been related to fuel injectors. Perform injector balance or AFIT test prior to going further. If normal diagnostics do not lead to a resolution for this concern, look for a small leak in the exhaust, usually at the outlet to the catalytic converter. This leak will allow air to be pulled into the exhaust and cause a false lean concern at the post O2 sensor. To diagnose this leak Chevy recommends applying air to the rear of the downstream converter or to the tailpipe on single systems at 5 to 8 psi. Apply a soapy solution to the gasket areas and the O2 sensor boss. Leaks in these areas that will cause the code will be larger bubbles. A foamy appearance should be considered normal.
If a leak is found, along with gasket replacement, filing the mating surface of the pipe is suggested. If no leaks are found at this point, you should look for a mechanical valvetrain concern such as a sticking valve, or a lifter follower off the camshaft. This may or may not cause a misfire.
If applying air to the exhaust, do not use full shop air. Regulate air to 5 to 8 psi to avoid damaging the converter.