Engine B16XNT 1.6 Turbo CNG (150 hp): Experiences, problems, fuel consumption and buying used
- Cheap running costs: Thanks to the factory CNG (methane) system, running costs are minimal compared to conventional petrol or diesel engines.
- Heavy body: With 200 Nm of torque, the engine is quite “lazy” in the heavy Zafira Tourer, especially under load.
- Sensitive ignition system: Running on methane requires a flawless ignition system – spark plugs and coils are consumables you must pay close attention to.
- Timing chain: There is no timing belt, but the chain stretches over time and needs to be replaced once it becomes noisy.
- Gearbox as a weak point: It is paired with the notorious M32 manual gearbox whose bearings often fail if the oil is not changed regularly.
- Cylinder inspection: When buying used, the most important item is the production date and validity of the inspection certificate for the factory methane cylinders.
Contents
- Introduction: An eco car that saves your wallet
- Technical specifications
- Reliability and maintenance
- Specific parts and costs
- Fuel consumption and performance
- Additional options and modifications
- Gearbox and drivetrain
- Buying used and conclusion
Introduction: An eco car that saves your wallet
Opel’s B16XNT engine is a rather specific beast. It is a 1.6‑liter turbo petrol unit purpose‑built (ecoFLEX) to run on compressed natural gas (CNG / methane). It was installed primarily in the Opel Zafira Tourer C (both before and after the 2016 facelift). The main selling point of this engine is not sporty driving, but pure math – it is designed for larger families and taxi drivers who cover huge mileages and want fuel costs at the level of riding a scooter. Still, the combination of a turbocharger, methane and a heavy body brings specific maintenance requirements that any experienced mechanic should warn you about.
Technical specifications
| Parameter | Data |
|---|---|
| Displacement | 1598 cc |
| Power | 110 kW (150 hp) |
| Torque | 200 Nm |
| Engine code | B16XNT |
| Injection type | Multipoint (Petrol / CNG) |
| Charging | Turbocharger |
Reliability and maintenance
This engine does not use a timing belt, but a timing chain drive. In theory that sounds like an advantage, but in practice the chain can stretch and the tensioner can weaken. The “major service” on this engine basically comes down to replacing the chain set with guides and tensioners. There is no strict factory interval for replacement; instead, its condition is monitored by ear – if you hear metallic rattling from the engine bay for a few seconds on the first cold start in the morning, it’s time for the workshop. On average, the chain lasts around 150,000 to 200,000 km before replacement becomes mandatory.
The sump takes about 4.5 to 5 liters of oil. The factory recommends 5W‑30 with dexos2 approval (or the newer dexos1 gen2, check according to the VIN). Due to the high combustion temperature of methane and the sensitivity of the turbocharger, forget about “long‑life” service intervals. Do the oil change strictly every 10,000 to 15,000 km. The engine tends to sip oil – consumption of around 0.3 to 0.5 liters per 1000 km, especially under load on the motorway, is considered normal for this design. If it uses more than that, the rings are probably stuck or the turbo is leaking oil.
As for ignition, the engine is extremely sensitive to spark quality. Methane has a higher ignition point and offers more resistance to spark jump than petrol. That’s why spark plugs need to be replaced much more often – mechanics usually recommend every 30,000 km. If you neglect the plugs, the coil pack will soon burn out, resulting in jerking under acceleration and loss of power.
Specific parts and costs
Although it is a petrol engine, due to the turbocharger and the need to smooth out power delivery to a heavy chassis, the B16XNT is fitted with a dual‑mass flywheel. Replacing it together with the clutch kit is a hefty expense for the owner, but fortunately it lasts quite a long time as long as you don’t abuse the car with hard launches at traffic lights.
The injection system is dual. You have petrol injectors and gas injectors. The petrol ones rarely fail on their own, but since the car runs on methane 90% of the time, they tend to seize up from lack of use. Tip: at least once a month, drive the car on pure petrol at higher revs. On the other hand, the gas injectors are very expensive and sensitive to contamination in the system (metal shavings from the installation or dirty gas). Symptoms of problems include difficulty switching to gas, rough idle or stalling.
The turbocharger (it has a single turbo) has a solid service life, provided you don’t switch the engine off immediately after hard driving uphill or on the motorway – let it idle for a minute or two so the oil can cool the turbo bearings. Good news for everyone who hates modern diesel emissions systems: This engine does NOT have a DPF filter, nor does it use AdBlue! It has a standard EGR valve and catalytic converter. The EGR valve tends to get clogged over time by oil vapors, which leads to engine hesitation at low revs, but it is relatively easy to clean.
Fuel consumption and performance
The Opel Zafira Tourer is a massive car, weighing over 1.6 tons empty. With 150 hp and a rather modest 200 Nm of torque, this engine feels subjectively lazy. While a diesel’s torque kicks in from around 1700 rpm, the B16XNT needs to be “revved out” to pull properly, especially when there are seven people on board with the air conditioning on.
As for fuel consumption, if you drive it exclusively on petrol, expect figures of 10 to 12 liters per 100 km in the city. However, almost nobody does that. On methane, in heavy city traffic, it will use around 6 to 8 kg of methane per 100 km. On open roads and country highways, methane consumption drops to about 4 to 5 kg. On the motorway at 130 km/h, the engine cruises at just under 3000 rpm. The Zafira’s sound insulation is excellent, so noise is not an issue, but any attempt at more aggressive overtaking will require dropping one or even two gears.
Additional options and modifications
People often ask whether LPG can be installed on this engine. The short and clear answer: No, and it makes absolutely no sense. This car leaves the factory with integrated cylinders and fully optimized software for CNG (methane). Adding an LPG system on top of the existing setup would be a technical hack job and a legal problem.
As for “chipping” (Stage 1), it is software‑wise possible to extract around 170 to 180 hp and a few dozen Nm more. Still, experienced mechanics rarely recommend it. Methane already creates high temperatures in the combustion chamber. Increasing turbo pressure and fuel quantity can easily lead to burnt valves or damaged pistons. If you feel you need more power, this simply isn’t the right car for you.
Gearbox and drivetrain
The engine is most commonly paired with a six‑speed manual gearbox bearing the notorious code M32. This is perhaps the biggest drawback of the entire drivetrain. M32 gearboxes suffer from poor cooling of the rear shaft bearings (sixth gear is most commonly affected). The symptom is a clearly audible whine under acceleration in 5th and 6th gear, followed later by the gear lever moving back and forth when you apply and release the throttle. To prevent this, it is essential to change the gearbox oil every 60,000 km. Many mechanics fill 200–300 ml more oil than the factory spec to ensure better lubrication of the upper bearings.
There are also versions with a 6‑speed conventional automatic (with a torque converter). It shifts smoothly and is comfortable, but further increases fuel consumption and makes the car feel more sluggish. The same rule of preventive maintenance applies to the automatic – flushing and oil replacement must be done strictly every 60,000 km to avoid failures of the valve body, which are extremely expensive to repair.
Buying used and conclusion
When buying a Zafira with the B16XNT, a standard mechanical inspection is only half the job. Besides listening for chain rattle (when cold), turbo whine and gearbox noise in sixth gear, the key issue is the methane cylinders.
The cylinders have an expiry date (usually 20 years from the production date), but they also require rigorous inspections and renewal of the certification every few years (the procedure differs from country to country). Before buying, ask for the inspection papers! Replacing the complete set of cylinders can cost more than half the value of the car itself.
Also, test how the car switches from petrol to methane and back. You should not feel any jerk. If the idle speed fluctuates heavily once the engine is warm, the problem may be an air leak, dirty injectors or a clogged EGR valve.
Who is it for? The Zafira 1.6 Turbo CNG with the B16XNT engine is a purpose‑built tool. It is not fun to drive, it is quite lazy for its weight and it requires a meticulous owner who won’t skimp on frequent spark plug and oil changes. But if you need a spacious seven‑seater family minivan that eats up miles for ridiculously little money, you will struggle to find a better and more cost‑effective option on the used‑car market.
