Error 0420 in Nissan: decoding, causes and solution to the problem

Error code 0420 on the instrument panel Nissan - one of those mysterious combinations that can cause panic even among experienced car owners. It appears unexpectedly, often accompanied by a flashing indicator CHECK ENGINE or SLIP, and the question immediately arises: how serious is this? Unlike obvious faults such as engine overheating or low oil level, an error P0420 (and this is how it is designated in diagnostic scanners) requires a more in-depth analysis.

This problem is typical for most modern models Nissan - from compact Juke And Note to full-size crossovers X-Trail And Pathfinder. In 90% of cases, it is related to the exhaust system, but the exact cause can vary from simple sensor wear to serious problems with the catalytic converter. In this article we will look at all possible scenarios, including those that official dealers often keep silent when offering expensive repairs.

It is important to understand: ignoring an error 0420 not only increases fuel consumption and loss of power, but also risks damaging other vehicle components. For example, long-term driving with a faulty catalyst can lead to its ceramic dust getting into the engine cylinders, which will result in a major overhaul. So let's figure out what to do if your Nissan produces this code.

What does error 0420 mean in Nissan?

Error P0420 (or 0420 on the instrument panel) stands for "Catalyst System Efficiency Below Threshold" - that is low efficiency of the catalytic system. Translated into simple language: your catalyst (or its control system) is working worse than required by environmental standards. But there is a nuance here: the code itself does not indicate a specific malfunction, but only signals a problem in the chain:

• 🔧 Catalytic converter - the main "suspect". Over time, its cells become clogged or destroyed, reducing throughput.
• 📊 Oxygen sensors (lambda probes) - front and rear. Their incorrect readings may falsely trigger an error.
• ⚡ Problems with the fuel system - rich or lean mixture, faulty injectors, air leaks.
• 🔥 Software glitches - rarely, but it happens that the error occurs due to a “glitch” of the control unit (ECU).

Interesting fact: on cars Nissan with engines HR16DE, MR20DE or QR25DE error 0420 often appears after 100–150 thousand kilometers, which coincides with the average resource of the original catalyst. However, in 30% of cases the problem lies not in it, but in the sensors or wiring. For example, on Qashqai J10 And X-Trail T31 The rear lambda probe, which is located after the catalyst and is responsible for monitoring its operation, often fails.

Another important point: error P0420 can be either constant (Pending Code), and periodic. If it disappears after a reset and appears again after 100–200 km, this is almost guaranteed to be a problem with the catalyst. If the error occurs chaotically (that is, then not), the sensors or electricians are most likely to blame.

The main reasons for error 0420

In order not to waste time and money on replacing working parts, you need to clearly understand what could have caused the error. We have collected all possible reasons, ranked by frequency of occurrence (from most likely to rare).

Reason	Frequency of occurrence	Symptoms
Catalyst wear	60–70%	Loss of power, increased fuel consumption, rattling sound under the bottom
Malfunction of the rear lambda probe	20–25%	The error appears randomly, there are no other symptoms
Problems with the fuel mixture	10%	Black smoke from the exhaust, smell of gasoline, errors in the oxygen sensor (P0171, P0174)
Mechanical damage to the exhaust system	5%	Loud roar under the bottom, vibrations
ECU software failure	<1%	The error appears after flashing or disconnecting the battery

The most common reason is clogged or destroyed catalyst. By car Nissan with a mileage of 150 thousand km, its cells often sinter or crumble, which leads to a decrease in throughput. As a result, the pressure in front of the catalyst increases, and after it drops, which is what the rear lambda probe records. By the way, on models with engines VQ35DE (For example, Murano Z50 or Pathfinder R51) catalysts fail more often due to higher exhaust gas temperatures.

The second most common reason is rear oxygen sensor malfunction. It is located after the catalyst and compares readings with the front sensor. If the rear lambda probe is lying (for example, due to contamination or an open circuit), the control unit Nissan decides that the catalyst is not working and displays an error 0420. In practice, replacing a sensor (article number, for example, 22690-4M015 for Qashqai J11) solves the problem in 80% of cases.

⚠️ Attention: If the error 0420 appeared after refueling at an unknown gas station, there is a high probability that low-quality fuel got into the tank. In this case, it is enough to drain the gasoline and flush the fuel system - the catalyst can “come off” on its own.

How to diagnose error 0420 yourself

Before going to the service center, you can check primary diagnosis on your own. For this you will need:

• 🔧 Diagnostic scanner (for example, ELM327 or Launch CReader).
• 🔍 Flashlight and mirror for inspecting the exhaust system.
• 📱 Smartphone with error reading program (for example, Torque Pro).

Step 1: Read the complete list of errors. Error P0420 rarely comes alone. It is often accompanied by codes P0130–P0167 (problems with lambda probes) or P0300–P0306 (misfire). For example, if together with 0420 There is P0171 ("lean mixture"), the problem is more likely in the fuel system, and not in the catalyst.

Step 2: Check the real-time sensor readings. Connect the scanner and look at the graphs of the front and rear lambda probes. Normal:

• 📈 The front sensor should fluctuate within the range 0.1–0.9 V (with a warm engine).
• 📉 The rear sensor should show an almost straight line around 0.7–0.8 V (if the catalyst is working).

If the rear sensor “jumps” as actively as the front sensor, the catalyst is not working. If the rear sensor shows 0 V or 1.1 V and does not change - it is faulty.

Step 3: Inspect the exhaust system. Stop the engine, allow the system to cool and check:

• 🔥 Presence of mechanical damage (dents, cracks) on the catalyst.
• 💨 Exhaust force - if you put your hand on the exhaust pipe at idle, the pressure should be moderate. If it blows too hard, the catalyst is clogged.
• 🎵 Extraneous sounds - rattling inside the catalyst indicates destroyed honeycombs.

If you don't have a scanner, you can use "by elimination":

1. Reset the error (by disconnecting the battery terminal for 10 minutes or using a scanner).
2. Drive 50–100 km in a gentle mode (without sudden acceleration).
3. If the error returns, the problem is serious. If not, it may have been a temporary glitch.

⚠️ Attention: On some models Nissan (For example, Almera N16 or Primera P12) error 0420 may appear due to faulty EGR valve. Check its operation - if the valve is stuck, the exhaust gases are redirected back to the intake, which distorts the sensor readings.

How to resolve error 0420: step-by-step instructions

Depending on the cause, ways to solve the problem vary from a simple sensor replacement to complex repairs. We have collected all working methods, starting with the simplest ones.

1. Replacing the lambda probe (rear oxygen sensor)

If diagnostics show that the rear sensor is faulty, replacing it will cost less than repairing the catalyst. For most models Nissan original sensors will fit:

• 🔧 Nissan 22690-4M000 (for Qashqai J10/J11, X-Trail T31/T32).
• 🔧 Denso 234-4207 (universal analog).
• 🔧 Bosch 0 258 006 537 (for engines MR20DD).

Replacement process:

1. Disconnect the negative terminal of the battery.
2. Find the rear sensor (it is located after the catalyst, closer to the muffler).
3. Disconnect the connector and unscrew the sensor with a wrench 22 mm.
4. Install the new sensor, connect the connector.
5. Reset errors using a scanner or disconnecting the battery.

Sensor cost: from 2,500 to 6,000 rubles. Replacement time: 20–30 minutes.

2. Cleaning or replacing the catalyst

If the problem is in the catalyst, there are two options:

• 🧹 Cleaning - suitable if the honeycombs are clogged with soot, but not destroyed. Use special fluids (for example, Liqui Moly Katalysator-Reiniger) or mechanical flushing.
• 🔄 Replacement - if the catalyst is destroyed or sintered. Original catalyst for Nissan costs from 30,000 rubles, but you can install a universal (from 8,000 rubles) or a flame arrester (from 3,000 rubles) with a sensor blende.

For cleaning:

1. Remove the catalyst (on most models it is secured with 4–6 bolts).
2. Soak it in the cleaner solution for 12 to 24 hours.
3. Rinse with pressurized water.
4. Dry and reinstall.

Important: cleaning only helps in 40% of cases. If the catalyst has already begun to crumble, it can only be replaced.

3. Checking the fuel system

If the error 0420 accompanied by codes P0171/P0174 (“lean/rich mixture”), the problem may lie in:

• 🔥 Dirty injectors (ultrasound cleaning or washing Wynn's).
• 💨 Air leaks (check the pipes, intake manifold gaskets).
• ⛽ Faulty fuel pump or pressure regulator.

For diagnostics:

• Check the pressure in the fuel rail (normal: 3–4 bar).
• Inspect the spark plugs - if they are black (rich) or white (lean), the problem is confirmed.

4. Lambda probe decoy (extreme case)

If the catalyst is removed (for example, replaced with a flame arrester), and the error 0420 continues to appear, you can install mechanical or electronic snag. A mechanical one (spacer) costs about 500 rubles, an electronic one (emulator) costs from 1,500 rubles. However, please note:

⚠️ Attention: Installing a decoy violates environmental standards and can lead to problems when passing a technical inspection. In addition, on some models Nissan (for example, with an engine VQ35DE) electronic snag may conflict with the ECU firmware, causing errors P0430 or P0421.

Cost of repairs in the service vs self-repair

Prices for fixing errors 0420 in official and independent services may differ greatly. Below is a comparison table for popular models Nissan:

Model	Diagnostics	Replacing the lambda probe	Catalyst replacement	Cleaning the catalyst
Qashqai J11 (1.6/2.0)	1 500–2 500 ₽	3 000–5 000 ₽	25 000–40 000 ₽	5 000–8 000 ₽
X-Trail T32 (2.0/2.5)	2 000–3 000 ₽	4 000–6 000 ₽	30 000–50 000 ₽	6 000–10 000 ₽
Juke F15 (1.6)	1 200–2 000 ₽	2 500–4 000 ₽	20 000–35 000 ₽	4 000–7 000 ₽
Pathfinder R52 (3.5)	2 500–4 000 ₽	5 000–8 000 ₽	40 000–70 000 ₽	8 000–12 000 ₽

Do-it-yourself repairs will be cheaper, but require time and tools. For example, replacing a lambda probe with your own hands will save 1,500–3,000 rubles, and cleaning the catalyst - up to 5,000 rubles. However, if we are talking about replacing the catalyst with Pathfinder or Patrol, you can’t do without service - you need a lift and welding equipment.

Average costs for self-repair:

• 🔧 Lambda probe: 2,500–6,000 ₽ (sensor) + 0 ₽ (work).
• 🧹 Catalyst cleaning: 1,000–2,000 ₽ (liquid) + 0 ₽ (work).
• 🔄 Universal catalyst: 8,000–15,000 ₽ + 2,000 ₽ (welding).

Prevention: how to avoid error 0420 in the future

Prevent the error from occurring 0420 easier than eliminating its consequences. Here 5 Key Recommendations for owners Nissan:

• ⛽ Refuel at proven gas stations. Poor gasoline with high sulfur content or additives accelerates catalyst wear.
• 🔧 Change spark plugs every 30–40 thousand km. Misfires cause unburned fuel to enter the catalyst, destroying it.
• 💨 Monitor the condition of the air filter. A clogged filter enriches the mixture, which increases the load on the catalyst.
• 🚗 Avoid long driving at low speeds. When driving in “lower” gears (for example, in traffic jams), the catalyst overheats.
• 🔥 Check for errors regularly with a scanner. Early detection of problems with lambda probes or the fuel system will prevent damage to the catalyst.

Pay special attention the first sign of trouble:

• 🔊 Extraneous sounds from under the bottom (rattling, rattling honeycombs).
• 💨 Increased fuel consumption (more than 1–1.5 liters per 100 km).
• 🚘 "Dullness" of the engine during acceleration (especially at speeds above 3,000).

If you often drive off-road or operate your vehicle in difficult conditions (for example, Navara or Patrol), recommended:

• Install catalyst protection (for example, a metal screen from Febi).
• Use fuel system cleaning additives (For example, Liqui Moly Systempflege Diesel for diesel Nissan).
• Check often exhaust system condition on a lift.

What happens if you ignore error 0420?

If you drive for a long time with a faulty catalyst, its ceramic dust can get into the engine cylinders, which will lead to scoring on the walls and wear of the piston rings. In the worst case, a major engine overhaul will be required (from RUB 100,000). In addition, increased resistance in the exhaust system increases the load on the turbine (if there is one), reducing its life.

FAQ: Frequently asked questions about error 0420 in Nissan

Is it possible to drive with error 0420?

Short term - yes, but not recommended. Long-term driving with a faulty catalyst or sensors can lead to:

• Increased fuel consumption by 10–20%.
• Loss of power (especially noticeable on engines VQ35DE And MR20DD).
• Damage to other components (for example, turbine or EGR valve).

If the error appears for the first time, you can go to the service center, but you should not delay repairs.

I reset error 0420, but it returned after 100 km. What to do?

This is typical behavior when faulty catalyst. Control unit Nissan fixes the error only after several check cycles. If it returns, the problem is definitely in the catalyst or rear lambda probe. Start by replacing the sensor (cheaper), if that doesn’t help, check the catalyst.

Is it possible to remove the catalyst and install a blende?

Technically yes, but there are some nuances:

• 🚗 On naturally aspirated engines (for example, HR16DE) it will pass without consequences.
• ⚠️ On turbocharged engines (for example, MR16DDT in Qashqai J11) Removing the catalyst can lead to overheating of the turbine.
• 📝 Since 2023, the removal of the catalyst has been officially prohibited (fine up to 50,000 ₽ when undergoing maintenance).

If you still decide to remove the catalyst, install flame arrester And high-quality blende (For example, Catalyst Emulator from RaceChip).

What analogues of lambda probes are suitable for Nissan?

For most models Nissan sensors from Denso, Bosch And NGK. Here is the compatibility table:

Original article	Analogue Denso	Analogue Bosch	Nissan models
22690-4M000	234-4207	0 258 006 537	Qashqai J10/J11, X-Trail T31/T32
22690-AL500	234-4144	0 258 006 567	Juke F15, Note E12
22690-31U00	234-4028	0 258 006 513	Pathfinder R51/R52, Murano Z50/Z51

When purchasing, pay attention to number of wires (usually 4, but on some models - 5) and cable length.

Can error 0420 appear due to bad gasoline?

Yes, and this is one of the most insidious reasons. Bad gasoline with high sulfur content or additives can:

• 🔥 Fill the catalyst honeycombs with soot in 1-2 refills.
• 💨 Disable lambda probes (especially on engines with direct injection, for example, MR20DD).
• 🚗 Cause detonation, which will lead to the destruction of the catalyst.

If the error appears after refueling, try:

1. Drain the gasoline and add high-quality fuel (for example, Gazpromneft G-Drive 98).
2. Add fuel system cleaner to the tank (Liqui Moly Benzin-System-Reiniger).
3. Drive 50–100 km at high speeds (3,000–4,000 rpm) to burn through the