GM 1.5 Turbo Engine Common Problems & Long-Term Reliability

In 2014, General Motors made a big splash with its brand-new powertrain family, the Small Gasoline Engine (SGE). This diverse range of small-displacement economy engines, ranging from 1.0-liter to 1.5-liter in displacement, was the perfect balance between fuel efficiency and potent performance. But, the myriad of GM 1.5 turbo engine problems might’ve overshadowed it.

Despite the clever engineering employed in creating these engines, there were inherent flaws. From turbocharger failure to incorrect oil pressure readings, it was plagued with countless problems, like cracked pistons, terrible blow-by, and the constant sight of the check engine light. So, are these GM 1.5 turbo engine problems that bad?

Most Common GM 1.5 Turbo Engine Problems

As clever as it may be deep inside, the frequency of GM 1.5 turbo engine problems might suggest that it can also be a problematic motor. We’ll focus predominantly on the 1.5 turbocharged models, that is the LFV and LYX engines. Moreover, we’ll also narrow this down to the variants that are sold here in the US, which were fitted in Buicks, Chevys, and GMCs.

Among the former, Chevrolet had the most commonly reported GM 1.5 turbo engine problems of the bunch. Some of these issues, in a nutshell, include experiencing turbocharger failure if you’re driving in cold weather. Not to mention, the myriad of other issues, such as the erratic oil pressure readings. And, the Check Engine Light (CEL) going off far too many times.

These are the most noteworthy GM 1.5 turbo engine problems, among a sea of other miscellaneous faults. Here are some of the most common issues you might encounter with the GM 1.5 turbo engines:

1. Turbocharger Failure At Lower Temperatures

The most infamous GM 1.5 turbo engine problem includes how the turbocharger would fail at colder temperatures. This can, in effect, prevent you from driving your car at all. And even if you’re able to get it going, it can leave a significant impact on your performance, as well as driveability. Worse, this issue can begin appearing with minimal mileage clocked in.

Apparently, moisture from the intakes can freeze up at lower temperatures, blocking airflow to the turbos. It should clear up once the intakes and engine heat up more. A Canadian owner noted the temperature to be as low as -45°C. There hasn’t been a permanent fix, other than dealers advising owners to buy a radiator cover, to then block off the turbo’s intercooler airflow.

As the turbocharger freezes and fails, it might otherwise prompt your car to activate its ‘limp home’ mode, which sharply restricts the speed you’re able to drive. Reading into the forums, we’ve noted one story, where an owner had their turbo fail in the middle of a long drive. It failed more than once, forcing them to abandon their car, only to have it affect their loaner car, too.

Another owner saw a “reduced power” message pop up on their dash, before losing power from the engine completely. In other cases, owners were nearly caught in rear-end collisions or horrible near misses, as their vehicles lost power. Unfortunately, this turbocharger issue is far too common. Unsurprisingly, its victims are mostly those who live and drive in colder weather.

2. Oil Pressure Readings Forever Staying In Flux

Oil pressure gauges the flow of oil into the engine, which affects lubrication as well as cooling. Generally, most of us needn’t have to worry about oil pressure. That is unless you have a GM 1.5 turbo engine. They tend to have a habit of never keeping oil pressure at an even level. Sometimes, it might not have enough pressure, or at other times, far too much of it.

Just for context, here’s what varying oil pressures denote, to see how much PSI is too low or high for a typical car engine:

• • 20-30 PSI (oil pressure while idling)
  • 25-65 PSI (normal oil pressure)
  • 45-70 PSI (it gets pressurized while driving)
  • >80 PSI (too much oil pressure)
  • <20 PSI (too little oil pressure)

Alas, GM’s 1.5 turbo engines don’t follow these general guidelines and have oil pressures that could fluctuate nearly all of the time. More often than not, reaching dangerous levels. One owner saw how their 1.5 engines could see the oil pressure skyrocket from 30PSI to 70PSI, even while idling or driving steadily. This then ties in with heavy oil consumption or oil burning.

While it’s common, oil pressure can fluctuate randomly. So much so, that it appears that GM’s dealerships and technicians couldn’t replicate the problem. They’d report back to owners that everything is normal, and it’s possibly a feature of the engine to run at too high or low of oil pressure. Still, owners remain concerned about long-term damage and wear to the engine.

3. Check Engine Light (CEL) Appears Very Regularly

As scary as it might seem, the Check Engine Light (CEL) is quite useful. It can alert you early on to a possible issue with your vehicle. You could then take this as an opportunity to have it checked out as quickly as you can, before the problems snowball into something worse. A CEL can even light up in your dash for simple issues, such as not tightening your gas cap properly.

In the case of those cars fitted with a GM 1.5 turbo engine, the CEL can appear far too frequently, even when there aren’t any problems. We’d call them false positives. Many owners of these engines spotted the CEL showing up, with no other noticeable signs and symptoms of underlying issues. This was confirmed when diagnosed with an OBD diagnostics scanner.

Once again, no error codes popped up, which means there aren’t any problems. Yet, it hasn’t failed to induce fear in those owners, who think that something bad is brewing. This does appear intermittently, making it hard for mechanics to replicate the issue. Therefore, there hasn’t yet been a permanent solution to this issue of the check engine light flashing or blinking regularly.

Owners are left with two fixes, as GM themselves never released a patch. The first is to bring along a diagnostics (OBD) scanner tool. Once a CEL does show up, plug that into your car, and see if there are any errors. If there aren’t, you can clear out the CEL from flashing on your dash. The other fix, as recommended by GM dealers, is to take the risk of ignoring the CEL altogether.

4. Cracked Or Melted Pistons (And Terrible Blow-By)

When GM’s new 1.5 turbo engines went into mass production with the Chevy Malibu, severe problems started appearing. The most memorable among them is how these engines can run so hot, due to poor cooling and engine management, that they could melt. The pistons themselves could melt, possibly turning your inline-4 engine into an operational inline-3.

Subsequently, this issue could create rough idling, shuddering, as well as horrible amounts of blow-by. Some have speculated to poor mapping with the ECM or fuel-air flow. This causes the engine to run lean (too much air, not enough fuel to burn). It’s exacerbated by the inclusion of the turbos, as the engine repeatedly goes in and out of boost, further adding heat and strain.

Other symptoms include seeing smoke from the engine, as well as burning oil (heavy oil use and consumption). Misfires can also happen, as you’ll notice a check engine light, on top of poor performance. The good news here is that this pre-ignition failure, which prompts a cracked or melty piston, isn’t as widespread. GM has identified the root cause to be the engine’s SPI system.

Or, ‘stochastic pre-ignition’. It can be easily fixed by heading over to a GM dealership and getting the engine control module (ECM) reprogrammed. According to a bulletin issued by GM to its dealerships, the motor oil should also be changed. They specifically name the ACDelco Dexos 1 full-synthetic oil. Alternatively, Mobil 1 oil for those affected cars sold in Canada.

GM SGE (Small Gasoline Engine) Specs & Features

So, what about this GM SGE engine family, then? At the turn of the 2010s, General Motors realized the design and built a new series of engines, made with efficiency in mind. Good MPG figures alone aren’t enough. Thus, their engine needed to also be decently performant, lower emissions, and reduce the NVH to a minimum.

The latter stands for Noise, Vibrations, and Harshness, which defines the unpleasant or discomforting sounds and vibrations that you’ll experience while driving. With all that in mind, GM succeeded in creating a lightweight, modestly powerful, fuel-efficient, low-emissions, and easy-going engine to fit into their smaller and cheaper economy cars.

GM’s SGE is also marketed as part of their ‘Ecotec’ (or in some other markets, ‘Microtec’) engines. On top of that, General Motors also sells this engine to their Chinese partner, SAIC Motors. Where, SGEs can be found on SAIC-made cars, too. There are four distinct configurations that an SGE engine can have:

• 1.0-liter (999cc, 61.0-cubic inch), turbocharged inline-3
• 1.1-liter (1,118cc, 68.2-cubic inch), inline-3
• 1.4-liter (1,399cc, 85.4-cubic inch), turbocharged inline-4
• 1.5-liter (1,490cc, 90.9-cubic inch), turbocharged inline-4

To make it happen, GM engineered an abundance of new and innovative technologies into their SGE collection of engines. For instance, all the aforementioned configurations (and many other unique or specialized variations) are made from just two engine blocks. This encompasses their 3- and 4-cylinder versions, as noted earlier.

GM SGE Engine Trivia, Facts, & Details

• A key aspect of the SGE Ecotec engine is its modularity, whereby components can be readily interchanged if needed. Hence, they all have the same 2.91-inch (74mm) bore, and 3.19-inch (81mm) bore spacing.
• The direct injection fuel rails are mounted with bushings onto the cylinder head and valve cover. This can aid in reducing the vibrations and loud ticking sounds from the injectors. Consequently, GM has claimed that their 1.0-liter SGE engine is 25% quieter than Ford’s similar 1.0-liter engine in the Fiesta.
• In addition, GM’s other attempts to reduce noise from this engine include using a bed-plate engine block. This helps to increase stiffness – thus reducing any rattling or loose sounds – and use a stiffened aluminum cam cover. Also, the inline-3 engines get a counter-rotation balancing shaft. Bolted onto the oil pump, it can further lower radiated noise, as well as let it idle more smoothly.
• All turbocharged SGE engines carry a Mitsubishi Heavy Industries one-stage, single-scroll turbo. These can spool up very rapidly, with around 90% of their peak torque arriving between 1,500 to 5,000 RPM. This is fairly low in the rev range. Plus, peak power is within the 5,600 to 6,000 RPM range. The turbo is also installed close to the cylinders, able to dole out speedy torque and throttle response.
• The engine is made mostly out of aluminum (block and head) and uses a composite intake manifold. This is all in the name of saving as much weight as possible, and the SGE is overall a small and light motor. It only weighs 216 lbs (98kg) for the bigger 1.4-liter engine, which is 44 lbs (20kg) lighter than its predecessor.