Smoke & Mirrors
Owners of a 2012 Chevy Aveo may comment about an SES light on. Initial diagnosis may display any of the following fuel trim and/or O2 sensor related codes: P0101, P0137, P0138, P0140, P0141, P0157, P0158, P0160, P0161, P0171, P0174, P0420, P0430, P1174, P1175, P2096, P2097, P2098, P2099, P2177, P2178, P2179, P2180, P2187, P2188, P2189, P2190, P2270, P2271, P2272 and/or P2273.
If normal SI diagnostics do not lead to a resolution and an intake vacuum leak or an exhaust leak is suspected, the use of a smoke machine (J41413-200 Evaporative System Tester) may be useful to find the leak.
For an intake leak, the smoke can be introduced into the brake booster hose or the engine oil dipstick tube. For best effect, covering the air intake before the MAF sensor to allow air pressure to build is recommended.
For an exhaust leak, placing the hose into the tailpipe sealed with shop towels proves to be effective. This method is very good for finding small leaks around the O2 sensor embossments and slight cracks in an intake plenum or gasket.