I've gone through a lot of threads and repaired my Sonic as issues have come up. I've compiled a list of issues for any new Sonic owner to be aware of.
I am hoping to keep this thread updated as people stumble across new issues.
Engine:
Your two choices include the 1.8 litre Naturally Aspirated and a 1.4 litre turbo. I have the most experience with the turbo model.
Common Between BOTH
-Cooling Accessories:
Common points of failure include: Coolant tank cracks, hose failure (ballooning, dry rot, cracking), thermostat housing/coolant outlet, plastic coolant elbows, t-fittings (primarily in the rear of the engine).
I would recommend checking coolant levels periodically, if you notice yourself leaking coolant, its time to do some investigating.
-Water Pump:
1.8: Tends to suffer from broken impellers due to the use of a plastic water pump. If you notice overheating, and no coolant loss, have your water pump replaced. Full metal ones are offered from both aftermarket and OEM vendors. This will offer a significant reliability upgrade.
1.4: Another coolant issue more exclusive to the 1.4 is covered in an extended TSB from Chevrolet. The water pump on these cars leak around the gasket. It can also result in premature water pump failure. If you notice that you're losing coolant and can't figure out where. Have the dealer inspect the water pump and seals. A TSB applies up to ANY SONIC UP TO 150k miles for replacement. This issue is more common for early model year vehicles 2012-2013, before the updated pump was used.
-EVAP: The evap purge valve commonly fails over an extended mileage. It is a wear part and costs $22 through Amazon. It is located on top of the engine towards the intake manifold, and can be replaced by anyone. Look for the check engine code related to "EVAP PURGE."
-Coil Packs: 50k-100k miles (or maybe never): These vehicles have coil packs that suffer corrosion and breakage over time. More common to humid and hot climates due to the engine and turbo creating more heat than on a typical N/A engine. The rubber boots tend to break down and dry rot allowing moisture to corrode the coil packs. Removing them carefully and doing an inspection while changing out spark plugs is recommended.
There are replacement kits sold: MSD manufactures an upgradedstock replacement.
Beck Arnley provides a repacked OEM AcDelco one for cheaper than direct.
You can also upgrade to LS V8 coils if you have a tune.
-Fans: Bearings can fail inside fans. Knocking on the inside of the shroud or bearing whine will be audible.
-Common to 1.8
-Timing Belt: The 1.8l has a TIMING BELT. It must be regularly replaced at the specified interval or risk complete engine failure.
-Intake Piping: The 1.8l suffers from dry rot cracks in the intake piping as the rubber becomes brittle over time. This can cause the vehicle to run rich and wreck your catalytic converter. Check your piping with a usual oil change. GM offers extended coverage options for this part, but aftermarket metal intakes are available eliminating this issue.
-Common to 1.4T
-PCV: The biggest single point of failure for this engine is the PCV system. If not diagnosed and fixed, expensive damage to the engine will result. When the PCV system fails it routes excessive quantities of oil back into the engine. While all engines are designed to burn off small amounts of oil, large quantities can cause piston cracking or piston ring failure, catalytic converter issues, and lack of proper lubrication due to loss of oil.
The issue is well documented. Suggested reading below.
The DIY fix that is referenced above: HERE
When completing this fix, you must replace your valve cover as well.
-PCV intake return line also crack over time. This is the hard ribbed plastic hose that travels from the top of the intake manifold back into the turbo.
- Turbo wastegates: many have experienced failure on these vehicles with extended mileage. The diaphragm or the spring, not sure what's used from the factory becomes weaker over time. You will typically see a P0299 underboost code.
GM diagnoses this issue as a failed turbo, which has led to others to misdiagnose it as a failed turbo. 90% of time, not the case. Why this is occurs is because GM does not offer replacement wastegates as its own part. The whole turbo assembly is replaced instead.
So, there are two main available aftermarket wastegate replacements: BNR's and Mamba (Ebay) both require a tune to function properly. Or you can junkyard pull your own.
-Cracked turbos: have been reported. Internal cracks leading to boost leaks. Rare to occur, but the vehicle will make you aware of the failure. Doing a boost leak test will show you wear the failure has occurred.
Chassis
-Sway Bar Links: Made of plastic... fail really early and cause loud banging in the front end. Recommended to replace with aftermarket options. Cruze links also fit without issue. Moog makes a good set with all metal and greasable joints.
-Engine Mounts: Pretty flimsy, tend to really degrade over time. This will cause mechanical loss due to the engine and transmission constantly rocking back and forth. Recommend to replace them when they start to wear. Including the lower transmission mount.
Transmission
-2nd Gear Grind: Common to all manual transmissions on the Sonic. If you have a 6 speed you have this issue. The true source of it is debatable but what you'll notice is that if you shift too quickly into 2nd gear at high RPMS 5500+, the transmission won't go into gear and grind.
Several proposed solutions have been to:
Recommended: Re-tighten/calibrate your shifter cables.
Recommended: Use a BNR or ZZP cable clamp.
Recommended: Drain and fill the transmission with Amsoil Synchromesh or SevereGear.
Recommended: Switching out the clutch valve with the Cruze and doing the delay valve delete.
Using a solid lower transmission mount.
Replacing shifter tower bushings with solid ones from companies like DDMWorks.
Replacing the shift cables (last resort option.)
Some more literature on the issue: FAQ: 2nd Gear Grind & Possible Solutions ~ Gamma II ?²
-Bearing failure: Mainly affecting early manual transmissions up to 2013.5 models. There are design flaws within the transmission that starve certain bearings of proper lubrication. This, coupled with poor cooling, and a low factory fill of transmission fluid result in premature bearing failure.
This issue was first noticed and documented by European drivers who received the M32 transmission before it came to the United States. There are several symptoms of this issue, including:
1. significant movement in the shifter in 5th & 6th gear,
2. whining/grinding noise in specific gears -- or all gears above 20mph,
3. and total gear and synchro failure at higher mileage, including the bearing shooting out of the casing.
The fix is to either rebuild the transmission, or replace the entire unit. New transmissions that were placed in production models around the 2013 model year feature a revised end case, bearing design, new clutch and flywheel, and are factory filled to a new higher level of 2.4 quarts rather than the 1.3. These features help increase the oil flow and cooling to prevent failure. A simple Google search will point you to the various changes of the M32 through British sources including the new look of the new end case.
Regardless of anything, make changing transmission fluid a more regular service item. Roughly every 50-70k miles (depending on driving tendencies). These transmissions are notoriously hard on their oil. Tunes & spirited driving can degrade the effectiveness of your lubrication.
mja said:
2nd gear M32 grind is from the early transmissions. The '13+ has more issues with 3rd gear going out. The'13+ M32 fixes are: heavier duty stock clutch, updated front cover with oil baffle and oil supply to bearings, built in cable reset on the shift tower. All excellent updates. The 2012 transmission cable position can be reset but not as accurately as the later design.
- Automatics: This transmission is generally pretty stout. It does however have an issue with the selector switch on the transmission stick causing problems with switching into gear.
- TCM: Transmission control module, may malfunction, causing missed shifts, shift and rev hangs, or sudden loud/violent shifting. This typically requires a reset or reprogramming. This issue is rare.
NOTE: this isn't a comprehensive repair guide. This is merely documentation and general guidance on issues you may experience or to look out for. ALWAYS consult your dealer or mechanic BEFORE conducting any repair work or diagnosis'. If you're not experienced DO NOT attempt to fix anything as you may cause more problems for yourself. You are responsible for your own vehicle as well as its regular maintenance as instructed by the owners manual.
CONSULT: CSMANS.COM FOR REPAIR MANUAL(s) AND INFORMATION.
THIS POST IS BEING EDITED AND COMPILED OVER TIME. IT IS NOT IN ITS FINAL FORM.
