Flame arrestor for Nissan Almera Classic: how to choose, install and avoid mistakes

Owners Nissan Almera Classic (N16) sooner or later face the problem of a burnt out catalyst - especially on cars with a mileage of 150,000 km. Replacing the original unit with a new one costs a lot of money, so many people choose a budget solution: installing a flame arrester. But here lies a lot of pitfalls: from incorrect selection of parts to installation errors that lead to engine check on the dashboard or even damage to the lambda probe.

In this article we will look at which flame arrester is suitable for Almera Classic with engines QG15DE (1.5 l) and QG18DE (1.8 l), how to install it correctly without consequences for the electronics, and what to do if it lights up after replacement Check Engine. We will also compare popular models of flame arresters in terms of price and service life, and provide a checklist for self-installation.

Why do you need a flame arrester instead of a catalyst on Almere Classic?

Catalytic converter in the exhaust system Nissan Almera Classic performs two functions: it cleans exhaust gases from harmful impurities (CO, CH, NOx) and reduces noise. Over time, the catalyst honeycomb becomes clogged or melted, which leads to:

• 🔥 Loss of power — the engine “chokes”, especially at speeds above 3000.
• 🚨 Error code P0420 (“Low catalyst efficiency”) and burning Check Engine.
• 💰 Increased fuel consumption - up to 1–1.5 liters per 100 km.
• 🔊 Increased noise — burnt honeycombs create a rattling sound.

A flame arrester solves these problems, but does not clean the exhaust. It is a perforated metal pipe with a filler (usually basalt wool or ceramics), which extinguishes the flame and reduces the temperature of the gases. On the Almera Classic, a flame arrester is installed instead of a standard catalyst in the exhaust pipe (the first one along the gas flow), and the second catalyst (under the bottom) is often left in place or replaced with a stronger.

Advantages of a flame arrester:

• ✅ Cost — 3–5 times cheaper than a new catalyst (from 1,500 to 4,000 rubles).
• ✅ Resource — if installed correctly, it lasts 80–100 thousand km.
• ✅ Easy to install — you can install it yourself in 1–2 hours.

⚠️ Attention: Removing the catalyst without replacing it with a flame arrester or stronger leads to breakdown of the exhaust system - gases will burn through thin-walled pipes for 5-10 thousand km. The load on the lambda probes also increases, which shortens their service life.

Which flame arrester to choose for Nissan Almera Classic

There are three types of flame arresters on the market for Almera Classic:

1. Universal - require welding and adjustment to size. Cheaper, but more difficult to install.
2. Ready-made (for a specific model) - for example, from Bosal or Walker. More expensive, but ideally fit into a regular place.
3. Sports (perforated) - for tuning, but can cause a lambda error due to altered gas flow.

For Almera Classic The optimal option is No. 2 - ready-made flame arresters for the flange of the standard catalyst. They maintain the geometry of the exhaust system and minimize the risk of errors ECU. Popular models:

Model	Manufacturer	Price, ₽	Features	Service life
MG-Race	Russia	2 200–2 800	Double-layer body, basalt fiber	80–100 thousand km
Fox 56.1001	Poland	3 500–4 200	Stainless steel, ceramic filler	100+ thousand km
Bosal 250-101	Netherlands	4 500–5 500	Original quality, precise fit	120+ thousand km
Walker 20636	Belgium	5 000–6 000	Reinforced design, minimal noise	150+ thousand km

Suitable for budget replacement MG-Race or Fox, if you need durability - Bosal or Walker. Please note the flange diameter: for Almera Classic he must be 50–52 mm (depending on the year of manufacture).

Step-by-step instructions for installing a flame arrester

The installation can be done independently if you have welding and a grinder. If you have no experience, it is better to contact the service (cost of work: 1,500–2,500 ₽).

Required tools:

• 🔧 Grinder with cutting wheel.
• 🔥 Welding machine (semi-automatic).
• 🔩 Set of keys (for 10, 12, 14).
• 🧲 Magnet for holding nuts.
• 🛠 WD-40 or a similar composition for unscrewing stuck bolts.

Cool the exhaust system (run on a cold engine)|

Disconnect the negative terminal of the battery |

Treat the catalyst mounting bolts with WD-40 30 minutes before starting work|

Prepare a new flame arrester and O-rings (if included)|

Check for the presence of blende or firmware for EURO-2 (if necessary) -->

Step 1. Removing the old catalyst

Lift the car on a lift or drive it into a pit. Unscrew the bolts securing the exhaust pipe to the manifold and resonator. If the bolts are stuck, cut them off with a grinder, but carefully so as not to damage the flanges. After removing the catalyst, clean the seats from rust and dirt.

Step 2. Installing a flame arrester

If the flame arrester is universal, cut it to the size of the old catalyst (length ~30–35 cm). Weld the flanges, maintaining the alignment of the pipes. For ready-made models, it is enough to install the O-rings and tighten the bolts to a torque 30–40 Nm.

Step 3. Checking the tightness

Start the engine and inspect welds/connections for leaks. If necessary, tighten the bolts or re-weld the seams. Pay attention to the exhaust sound - it should be smooth, without popping.

⚠️ Attention: If after installing the flame arrester the Check Engine with an error P0420 or P0134 (lambda probe malfunction), you must:

• Install mechanical snag (welded in front of the second lambda probe).
• Or flash it ECU to EURO-2 standards (disables catalyst testing).

Without these measures, the engine will operate in emergency mode and fuel consumption will increase.

Common installation mistakes and how to avoid them

Even experienced technicians sometimes make mistakes that lead to problems with the exhaust system or electronics. Let's look at the most common ones:

1. Incorrect choice of flame arrester - for example, installing a perforated model without filler. This leads to sharp exhaust sound and rapid burnout of the pipe.
2. No decoy/firmware - if you do not disable the catalyst control, ECU will log an error P0420 and limit power.
3. Poor sealing of welds - even a small gas leak leads to air leaks and false readings from lambda probes.
4. Ignoring the second catalyst - if you leave it in place, it will quickly clog due to the altered flow of gases.

To avoid problems:

• 🔍 Before purchasing a flame arrester, check its compatibility with your modification Almera Classic (engine QG15DE or QG18DE).
• 📏 Measure the diameter of the flanges - they must match the original ones (standard: 50–52 mm).
• 🔧 Use stainless steel bolts and nuts - ordinary ones quickly rust and stick.

💡

If, after installing the flame arrester, a metallic ringing occurs when the engine is running, most likely, the ceramic filler inside the housing has broken off. In this case, you will have to replace the flame arrester - it cannot be repaired.

Comparison of flame arrester and stronger: which is better for Almera Classic

In addition to the flame arrester, Nissan Almera Classic often installed stronger - a straight section of pipe without filler, but with thickened walls. Let's compare both options:

Criterion	Flame arrestor	Stronger
Cost	2 000–6 000 ₽	1 500–3 000 ₽
Noisiness	Moderate (close to drain)	Increased (sound "sporty")
Resource	80–150 thousand km	50–80 thousand km (burns out faster)
Effect on lambda probes	Minimum	High (risk of errors)
Difficulty of installation	Medium (needs welding)	Simple (you can do without welding)

Conclusion: flame arrester preferable for daily use as it lasts longer and does not increase noise. Stronger cheaper and easier to install, but suitable only for a temporary solution or tuned cars.

💡

If your Almera Classic has traveled more than 200 thousand km, the best option is a flame arrester Fox or Bosal + lambda probe snag. This will save money on fuel and avoid mistakes ECU.

What to do if the Check Engine lights up after installing the flame arrester

Error P0420 (“Low catalyst efficiency”) or P0134 (“No oxygen sensor signal”) appears in 90% of cases after removing the catalyst. Reason - ECU detects a change in the composition of the exhaust gases and considers this a malfunction.

Solutions:

1. Mechanical snag - welded into the pipe in front of the second lambda probe. Creates an “emulation” of the catalyst’s operation by reflecting some of the gases.
2. Electronic snag — connects to the lambda probe wires and corrects the signal. Less reliable, but easier to install.
3. ECU firmware for EURO-2 — disables catalyst control in the control unit. The most radical, but also the most effective solution.

For Almera Classic More often they use mechanical blende (cost: 500–1,000 rubles). Electronic snag can malfunction due to sudden temperature changes, and the firmware requires access to chip tuners (price: 3,000–5,000 ₽).

Algorithm of actions in case of error:

1. Read the error code by the scanner (for example, ELM327).
2. If the error P0420 - install a fake or flash it ECU.
3. If the error P0134 — check the lambda probe circuit (possibly damaged during welding).
4. Reset the error using a scanner or by disconnecting the battery for 10 minutes.

⚠️ Attention: If the error does not disappear after installing the fake, check exhaust system tightness. Air leaks through loose connections or cracks lead to false alarms of the lambda probe.

Flame arrestor maintenance: how to extend its service life

The flame arrester does not require regular maintenance, but a few simple rules will help avoid premature failure:

• 🚗 Avoid prolonged idling - this leads to overheating and melting of the filler.
• 💨 Monitor the condition of the exhaust system — rust on flanges or pipes accelerates the destruction of the flame arrester.
• 🛢 Use quality fuel — bad gasoline increases the exhaust temperature and reduces the life of the filler.
• 🔧 Check the fastenings — vibration weakens welds and bolted joints.

Average flame arrester life per Almera Classic — 80–100 thousand km. Signs of wear:

• 🔊 Increased exhaust noise (ringing, rattling).
• 🔥 Sparks appearing from under the bottom (perforation burnt out).
• 💨 Deterioration of traction at high speeds.

If the flame arrester filler has collapsed, it can be refill (replace basalt wool or ceramics). Cost of the service: 1,000–1,500 rubles. However, this is a temporary solution - after 20-30 thousand km the problem will return.

What happens if you drive with a destroyed flame arrester?

Ignoring the problem leads to:

- Filler particles getting into the cylinders (risk of scoring on the walls).

- Overheating of the exhaust system and burnout of the resonator/muffler.

- Damage to lambda probes due to elevated gas temperatures.

In critical cases, engine repair may be required (cost from 20,000 ₽).

FAQ: Frequently asked questions about flame arresters on Nissan Almera Classic

Is it possible to install a flame arrester without welding?

Theoretically yes, if used flange connections with clamps. However, such installation is unreliable: over time, the joints will depressurize, air leaks and lambda probe errors will appear. Welding is recommended for durability.

Will the flame arrester pass inspection?

From 2022, Russia has abolished exhaust gas testing for TO for cars over 4 years old (including Almera Classic). However, if the inspector wants to check visually, the absence of a catalyst may be a reason for failure. In this case, installing strongera instead of a flame arrester (looks like a standard pipe).

Which flame arrester is the quietest?

Models with double-layer casing and ceramic filler (for example, Walker 20636 or Bosal 250-101) provide minimal noise, close to a standard catalyst. Perforated or empty strongers sound much louder.

Do I need to flash the ECU after installing the flame arrester?

Not required, but recommended if you want to avoid mistakes P0420. The alternative is mechanical snag. Firmware for EURO-2 provides additional advantages: engine responsiveness improves and fuel consumption decreases by 5–7%.

Is it possible to drive without a flame arrester by simply cutting out the catalyst?

Absolutely not. Without a flame arrester or stronger, the flow of hot gases will quickly burn through the thin-walled pipes of the exhaust system (especially the resonator). In addition, the load on the lambda probes will increase, and they will fail after 10–20 thousand km.