The customer returned after the catalytic converter was replaced and the P0420 reset. The scan tool P0420 - Catalyst System Low Efficiency. Campaign 14801A (Emissions Reflash) was completed at GM dealer.
Freeze Frame data is inconclusive, shows code set at 700 RPM, fully warmed up, off-idle throttle. Current LTFT +9%, STFT +/- 3%.
Comment(0)1 Repair(s) Available
TECH-ASSIST01/03/2018 | 07:28:36
The Tech smoke tested the exhaust system and found an exhaust leak where the cat bolts to the exhaust manifold. He replaced the gasket, no exhaust leak and the code does not reset.
Reprogram Engine Control Module Carbon Monoxide Emissions - 2011-2013 Chevrolet Cruze
General Motors and US Environmental Protection Agency emissions testing found vehicles that did not comply with the carbon monoxide emissions standard on the US06 emissions test.
2013-2017 Buick Encore
2011-2016 Chevrolet Cruze
2012-2016 Chevrolet Sonic
2013-2017 Chevrolet Trax
All equipped with 1.4L engine
There have been problems with P1101 set in the Cruze or Sonic with the 1.4 turbo engine. Lean codes may also be set with possible rough running or idle surge complaints.
The problem is caused by unmetered air entering the engine through the PCV system. The P0420 trouble code will appear first before P1101 as the parameters are much more sensitive, do not replace the converter until a proper diagnosis has been performed. Several PI's have been published to address this problem. PIP5197 and PI0907B- (PI0907Bsuperseded by PI0907C) among others. The first place to check is the throttle position angle with GDS2. A normal reading at hot idle is 8-12%. With a failure, the number will be much lower, usually 0-1% although less than 7% may indicate a problem.
The first place to check is the PCV orifice external port on the top of the cam cover. Vacuum should not be present at the port, if so, the cover must be replaced. If not, remove the PCV tube from the intake manifold and tape off the opening. Do the angle readings increase to normal? If so, replace the PCV tube.
Now you need to inspect for the root cause of the failure. Look into the PCV port in the manifold for a small orange tip of the non return protruding into the passage. If this tip is not visible, the non return valve is either missing or not seated which has damaged the other components from excessive vacuum and the manifold and turbo itself must be replaced.
If your angle readings still have not returned to normal, there is still a possibility of porosity in the PCV passage in the cylinder head. Check the crankcase pressure at the dipstick tube. It should read from -11 to -18 in. of water. If the reading is higher, the cylinder head passage must be tested for porosity.