2016 Smart Fortwo 0.9L Intake Manifold: Diagnosing Leaks, Rough Idle, and Boost Loss
Your complete guide to identifying, inspecting, and replacing the intake manifold on the 2016 Smart Fortwo with the 0.9L turbo engine.
- Compatibility is critical: This part is ONLY for the 0.9L Turbo engine, not the 1.0L. Verify OEM part number 2810900637 or 140039911R.
- Failure symptoms are typically a hissing noise, rough idle, and loss of power, caused by a crack in the plastic or a failed gasket.
- There are no recalls for this part, but a rough idle can also be caused by a faulty VVT solenoid, so proper diagnosis is important.
- Complete aftermarket manifolds are not widely available, making a verified, crack-free used OEM part a strong value alternative to expensive new OEM.
Symptoms of a Failing Intake Manifold
A problem with the intake manifold on the 2016 Smart Fortwo almost always involves a crack in its plastic body or a failed gasket. This allows unmetered air to leak into the engine (a vacuum leak) or pressurized air to leak out (a boost leak). The symptoms are often distinct and can appear gradually.
- Rough or Unstable Idle: This is one of the most common signs. The engine may shake, sputter, or have an RPM that bounces up and down at a stop because the extra, unmetered air disrupts the computer's calculations for the air-fuel mixture.
- Audible Hissing or Whistling: You may hear a distinct hissing sound coming from the rear engine compartment. This is the sound of air being sucked through a crack or a bad gasket seal. The noise often gets louder or changes pitch when you press the accelerator.
- Loss of Power and Hesitation: When you accelerate, the car may feel sluggish or hesitate. A leak prevents the engine from getting the correct air-fuel mixture and can cause a loss of boost pressure from the turbo, resulting in poor performance.
- Check Engine Light: A leak will almost certainly trigger a Check Engine Light. Common trouble codes include P0171 (System Too Lean), which indicates too much oxygen in the exhaust, or codes related to the Manifold Absolute Pressure (MAP) sensor, such as P0106 or P0107, if the sensor's readings are out of the expected range due to the leak.
- Reduced Fuel Economy: Your car's computer will try to compensate for the extra air by injecting more fuel, leading to a noticeable decrease in gas mileage.
Known Issues, Recalls, and TSBs
As of mid-2024, there are no active recalls or Technical Service Bulletins (TSBs) from Mercedes-Benz or the NHTSA specifically for the intake manifold on the 2016 Smart Fortwo.
While the part itself is not under recall, several safety recalls were issued for the 2016 model for other components. These include issues with the parking brake lock nut, improper headlight adjustment seals, and a potential failure of the left front steering knuckle. It is wise to have a dealer check your Vehicle Identification Number (VIN) to ensure these recalls have been completed.
Pro Tip: The 0.9L engine is known to have issues with a sticking Variable Valve Timing (VVT) solenoid, which can also cause a very rough idle. If your primary symptom is a rough idle without an obvious hissing sound, it's important to diagnose both the intake system and the VVT system to avoid replacing the wrong part.
Buying a Used Intake Manifold
Since new aftermarket options for this specific manifold are not readily available, a quality used OEM part is often the best value. However, careful inspection is critical before you buy.
Compatibility Check
Warning: This manifold only fits the 0.9L (898cc) turbocharged engine. It will NOT fit the 1.0L naturally aspirated engine found in some base models. Before purchasing, verify the OEM part number. The correct numbers are 2810900637 (Mercedes-Benz) or 140039911R (Renault).
Physical Inspection Points
- Check for Cracks: Meticulously inspect the entire plastic housing, especially around the seams where the pieces are molded together and at the mounting points where bolts apply pressure. Pay close attention to the base of any vacuum ports.
- Look for Warping: Place the manifold's engine-side mounting flange on a known flat surface. If there are any significant gaps, the manifold is warped and will not create a proper seal, even with a new gasket.
- Inspect All Ports: Check that all the small plastic nipples for vacuum lines are present and not cracked or broken off. These are fragile and can be easily damaged during removal from the donor vehicle.
- Check the MAP Sensor: See if the used manifold includes the Manifold Absolute Pressure (MAP) sensor. If it does, inspect its connector for corrosion or damage. If it doesn't, you will need to transfer yours from your old manifold.
Cost of Replacement
Replacing the intake manifold involves significant labor due to the part's location in the compact, rear-engine bay.
| Part / Service | Estimated Cost | Notes |
|---|---|---|
| New OEM Manifold | $350 - $500+ | Price can vary significantly by dealer. May need to be special ordered. |
| New Aftermarket Manifold | Not Available | Complete aftermarket manifolds for this specific model are not common. |
| Used OEM Manifold | $100 - $250 | Commonly found on eBay or from specialized auto recyclers. Price depends on condition and included sensors. |
| Shop Labor | $300 - $550 | Labor typically runs 3-5 hours. The job requires removing several connected components. |
| Gaskets & Seals | $15 - $40 | Always replace the main intake gasket and any other seals. They are not reusable. |
Replacement Overview
- Difficulty Rating: 4 out of 5 (Difficult)
- Estimated Time: 3-5 hours
- DIY Feasible?: Yes, for experienced mechanics. This is not a beginner-friendly job due to tight access in the rear engine bay and the number of connections (fuel lines, sensors, vacuum hoses) that must be disconnected and reconnected correctly.
Pro Tip: On models with the Twinamic dual-clutch transmission, the intake manifold must be removed to access and replace the upper clutch actuator motor. If you are having work done on the transmission that requires this, it is an excellent time to proactively replace the intake manifold gaskets to prevent future leaks.
Frequently Asked Questions (FAQ)
Can I drive my Smart Fortwo with a cracked intake manifold?
It is not recommended for long. While the car may be drivable, you will experience poor engine performance, stalling, and terrible fuel economy. Ignoring the problem can lead to engine damage over time as the computer struggles to maintain the correct operating conditions.
Do I have to replace the gaskets when installing a used manifold?
Yes, absolutely. Intake manifold gaskets are single-use, crush-style seals. Reusing an old gasket will guarantee a leak. New gaskets are inexpensive and are required for a successful repair.
Is this the same intake manifold used on a Renault?
Yes. The 0.9L engine in the 2016 Smart Fortwo is a Renault-Nissan H4Bt engine, which is also used in cars like the Renault Clio and Captur. The part may be cross-referenced under Renault part number 140039911R.
Could my problem just be the MAP sensor?
Yes. A faulty Manifold Absolute Pressure (MAP) sensor can cause very similar symptoms, including a rough idle, hesitation, and specific fault codes (P0105-P0109). If you do not have an audible hissing sound, it is worth diagnosing the MAP sensor before condemning the entire manifold.
Technical Specifications
OEM Part Numbers: 2810900637 A2810900637 140039911R 210452448R
Material: Plastic Engine Application: 0.9L (898cc) Turbocharged 3-Cylinder (Renault H4Bt)
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
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