Error P0303 on Nissan: misfire in cylinder 3 - causes and solutions

Fault code P0303 on the dashboard Nissan indicates misfire in third cylinder engine. This error doesn't just annoy the driver with a flashing light. CHECK ENGINE - it directly affects the dynamics of the car, fuel consumption and can lead to serious damage if the problem is ignored. Owners Qashqai, X-Trail, Juke and other models with gasoline engines HR16DE, MR20DE or QR25DE encounter it most often, but the reasons can differ radically - from banal candles to problems with ECU.

In this article we will look at all possible causes of error P0303, from simple to complex, and also give step-by-step instructions for diagnosis and repair. You will learn how to check the cylinder yourself, what tools you will need, and when it is best to contact service. We will pay special attention specifics of Nissan engines with variable valve timing (VVT), where misfires are often associated with faulty solenoids or timing chain.

What does P0303 mean on Nissan?

Code P0303 stands for "Cylinder 3 Misfire Detected" - that is misfire detected in the third cylinder. Electronic control unit (ECU) detects this malfunction when the crankshaft rotation speed deviates from the norm precisely at the moment of operation of the 3rd cylinder. The system analyzes data from the crankshaft, camshaft and oxygen sensors, comparing them with reference values.

It is important to understand that P0303 is not a cause, but an effect. The code itself does not say what exactly is broken, but only indicates the problem cylinder. The reasons may be mechanical (wear of the piston group), electrical (breakdowns in the wires) or related to the fuel system (clogged injectors). On Nissan with turbo engines (MR16DDT, M9R) the error is often accompanied by a code P0300 — random misfires on all cylinders, which complicates diagnostics.

• 🔧 Mechanical reasons: low compression, ring wear, valve damage.
• ⚡ Electrical problems: faulty spark plugs, coils, high voltage wires.
• ⛽ Fuel system: clogged injectors, low fuel pressure, low-quality gasoline.
• 📶 Electronics: malfunctions of sensors (crankshaft, camshaft, oxygen).

On Nissan Qashqai J11 And X-Trail T32 with motors MR20DD error P0303 often appears after refueling with low-quality fuel or when driving on gas (HBO). In such cases, misfires can be temporary and disappear after changing the fuel, but ignoring them is dangerous - prolonged work with a faulty cylinder leads to catalyst overheating and its destruction.

The main symptoms of misfire in cylinder 3

The P0303 code rarely appears on its own; it is usually accompanied by noticeable changes in the vehicle's behavior. Here are the key signs that will help confirm the problem:

• 🚗 Unstable engine operation at idle speed (vibration, “triple”).
• 💨 Power drop when accelerating, especially at low and medium speeds.
• 🔥 Increased fuel consumption (10–20% higher than usual).
• 🎯 Popping sounds in the exhaust system or muffler (indicates incomplete combustion of fuel).
• 🛑 Sunbathing CHECK ENGINE with possible transition to emergency mode.

On Nissan Juke with turbo engine HR16DET Misfires in cylinder 3 often occur jerking when changing gears, especially on an automatic transmission CVT. In some cases, the engine may stall when the gas is suddenly released. If you ignore these symptoms, over time the P0303 code will lead to damage to the catalytic converter, the repair of which will cost 30–50 thousand rubles.

⚠️ Attention: If the indicator comes on along with P0303 OIL PRESSURE (oil pressure), stop the engine immediately! This may indicate critical problems with the piston group or connecting rod bearings.

Step-by-step diagnosis of error P0303 on Nissan

To accurately determine the cause of misfires in cylinder 3, follow these instructions. Let's start with simple checks that you can do yourself, and gradually move on to more complex ones.

1. Checking the spark plugs

Spark plugs are the first and most common cause of the P0303 code. On Nissan It is recommended to use original spark plugs NGK IFR6A11 or Denso FK16HR11. If the spark plug is in cylinder 3:

• 🔥 Oily — a problem with valve stem seals or piston rings.
• 💧 Wet — fuel overflow (injector or ECU is faulty).
• 🧱 With carbon deposits - poor quality fuel or rich mixture.
• 🔌 Crack on the insulator - breakdown, replacement required.

To check, unscrew the spark plug from cylinder 3 (the order of the cylinders is Nissan usually considered from the timing belt) and compare it with others. If there are external differences, replace the spark plug with a new one and reset the error. If the P0303 code disappears, the problem is solved.

2. Checking the ignition coil

On Nissan with the system COP (individual coils for each cylinder) coil failure is the second most common cause of P0303. To check the cylinder 3 coil:

1. Remove the coil and inspect for cracks or melting.
2. Swap the coils of cylinders 3 and 1.
3. If the error has moved to 1 cylinder (P0301) - the coil is faulty.

The resistance of the primary winding of the coil must be within the range 0.5–1.0 Ohm, secondary - 8–12 kOhm (depending on the model). Checked with a multimeter.

3. Compression check

Low compression in cylinder 3 is a serious problem requiring engine repair. Normal values for Nissan:

• HR16DE: 12–14 bar.
• MR20DE: 13–15 bar.
• QR25DE: 11–13 bar (dispersion between cylinders is no more than 1 bar).

If the compression in cylinder 3 is lower by 20% or more, the reasons may be:

• 🔧 Wear of piston rings.
• 🔧 Valve burnout.
• 🔧 Damage to the cylinder head gasket.

For an accurate diagnosis, use pneumatic tester or pour 5-10 ml of oil into the cylinder - if the compression temporarily increases, the rings are to blame.

4. Checking the fuel system

If the spark plugs and coils are in order and the compression is normal, the problem may lie in the fuel system:

• ⛽ Injector 3 cylinders: Check the resistance (usually 12–16 Ohm) and productivity (on the stand).
• ⛽ Fuel pressure: must be 3.5–4.0 bar at idle (checked with a pressure gauge on the ramp).
• ⛽ Fuel filter: Clogging leads to a lean mixture and misfires.

On Nissan with direct injection (GDI) injectors often become clogged with deposits. For cleaning, use special additives (Liqui Moly Jectron) or ultrasonic cleaning.

5. Diagnostics of sensors and ECU

If all previous checks have failed, the problem may be:

• 📊 Crankshaft sensor (CKP): in the event of a malfunction, misfires appear in all cylinders, but may be more pronounced in the 3rd.
• 📊 Camshaft sensor (CMP): affects valve timing.
• 📊 Lambda probes: Incorrect readings lead to incorrect correction of the fuel mixture.
• 🤖 ECU: Firmware glitches or hardware malfunctions (rare, but possible).

To check the sensors, use a scanner (ELM327 or professional Launch). Compare readings with reference values for your model Nissan.

Sensor	Normal values (at idle)	Symptoms of a problem
Crankshaft sensor (CKP)	Signal: 5–7 V (amplitude)	Misfires in all cylinders, engine stalls
Camshaft sensor (CMP)	Signal: 0.3–4.5 V (square wave)	Errors P0340, P0345, unstable idle
Lambda probe (bank 1, sensor 1)	Voltage: 0.1–0.9 V (cyclic)	Rich/lean mixture, errors P0130–P0167
Absolute pressure sensor (MAP)	0.2–0.7 V (at idle)	Skips under load, error P0106

Common Causes of P0303 on Popular Nissan Models

Some models Nissan have “diseases” associated with misfires in cylinder 3. Let's look at the most common cases.

Nissan Qashqai (J10, J11) with HR16DE engine

On these vehicles, the P0303 code is often associated with:

• 🔧 Worn oil seals (oil enters the combustion chamber, the spark plugs become oily).
• ⚡ Breakdown of the ignition coil (original coils last ~100 thousand km).
• 🛢️ Clogged injectors (especially when driving on gas).

Solution: replacing caps, coils and cleaning injectors. After the repair, be sure to update the ECU firmware to the latest version - in older versions there were bugs with correction of the fuel mixture.

Nissan X-Trail (T31, T32) with MR20DE engine

On X-Trail With this engine, P0303 often appears due to:

• 🔥 Overheating cylinder 3 (problems with the cooling system or thermostat).
• 🔧 Piston ring wear (typical for runs over 150 thousand km).
• 📶 Knock sensor malfunctions (code P0325).

Feature: MR20DE often breaks down phase regulator on the intake camshaft, which leads to phase disturbances and misfires. Check for errors P0011 or P0021.

Nissan Juke with HR16DET engine (turbo)

On turbocharged Juke P0303 is often accompanied by:

• 💨 Air leak through cracks in the intercooler or pipes.
• 🔥 Re-enrichment of the mixture due to a faulty valve PCV.
• ⚡ Problems with the turbine (cartridge wear, blades jamming).

Diagnostics: check the boost pressure (should be ~1.2 bar at 3000 rpm) and inspect the pipes for cracks. The turbine on the HR16DET often fails after 120 thousand km.

Nissan Note and Tiida with HR16DE engine

On these compact models, P0303 is usually caused by:

• 🔌 Oxidation of ECU contacts (the unit is under the passenger’s feet, moisture gets in).
• 🔧 Worn valve guides (oil in the combustion chamber).
• ⛽ Poor quality gasoline (nozzles become clogged after 1–2 refills).

Solution: cleaning the ECU contacts, replacing valve seals and flushing the fuel system.

What to do if P0303 appears only when cold?

If the misfires only occur during a cold start, the problem is most likely valve stem seals (oil drains into the cylinder overnight) or in air leaks through cracks in the manifold, which “close up” when heated. Check also thermostat - if the engine does not reach operating temperature for a long time, the ECU enriches the mixture, which leads to misfires.

How to Troubleshoot P0303: Step-by-Step Instructions

Depending on the cause found, the repair methods will be different. Below are detailed instructions for the most common cases.

1. Replacing spark plugs and ignition coils

If the problem is in the spark plugs or coils, follow this algorithm:

1. Disconnect the negative terminal of the battery.
2. Remove the decorative engine cover (if equipped).
3. Disconnect the cylinder 3 coil connector and unscrew the mounting bolt.
4. Remove the coil and spark plug (use a 16mm spark plug wrench).
5. Install new parts (spark plugs NGK IFR6A11, original coils or Hitachi).
6. Reset the error with a scanner or by disconnecting the battery for 10 minutes.

Cost of a set of candles: ~1500–2500 rubles. Reel: ~3000–5000 rub. per piece (original).

2. Cleaning or replacing injectors

To wash the injectors without removing them:

1. Buy a cleaner (Wynn's or Liqui Moly).
2. Connect the cylinder to the fuel rail through the adapter.
3. Start the engine and let it idle for 10-15 minutes.
4. Repeat the procedure 2-3 times at intervals of 100 km.

If washing does not help, the injectors need to be removed and checked on a bench. Cost of cleaning one nozzle: ~500–800 rubles.

3. Repair of the piston group (low compression)

If the compression in cylinder 3 is below normal, engine disassembly will be required. Typical work:

• Replacing valve stem seals: ~5000–8000 RUR. (with work).
• Replacement of piston rings: ~15,000–25,000 rub. (depending on the motor).
• Grinding valves or replacing guides: ~10,000–15,000 rubles.

On Nissan with timing chain drive (For example, MR20DE) When disassembling the engine, it is recommended to replace the chain and shoes, even if they are visually normal.

4. Elimination of air leaks

To search for suction:

1. Stop the engine and remove the intake manifold.
2. Blow compressed air (2–3 bar) through the throttle hole, first blocking all branches.
3. Apply a soap solution to the connections - bubbles will indicate the location of the leak.

Frequent places of suction on Nissan:

• 🔧 Pipe from the valve PCV to the intake manifold.
• 🔧 Throttle valve gasket.
• 🔧 Cracks in the plastic intake manifold (typical for Qashqai J10).

5. ECU firmware update

If all mechanical causes have been ruled out and P0303 remains, the problem may be in the firmware. To update:

1. Download the latest software for your ECU (e.g. Hitachi H23 or Bosch ME7).
2. Connect to the diagnostic connector via K-Line or CAN.
3. Use the program WinFlash or ECUFlash for flashing.

Cost of service in the service: ~3000–5000 rub. Independent firmware is risky - if there is an error, the ECU may become damaged.

When to contact the service: difficult cases

Some causes of the P0303 code require professional diagnosis and repair. Contact the service if:

• 🔧 After replacing spark plugs, coils and injectors, the error remains.
• 🔧 Compression in cylinder 3 below 8 bar (major overhaul required).
• 🔧 There is a suspicion of a malfunction ECU (codes P0600–P0606).
• 🔧 Engine troit even after resetting the error.
• 🔧 Additional errors appear related to turbine (P0234, P0299) or timing phases (P0011, P0021).

Cost of diagnostics in the service: ~1500–3000 rubles. Use supported equipment oscilloscope - this will allow you to accurately determine the cause of omissions from the sensor signal graph.

⚠️ Attention: If found in the cylinder metal particles (during disassembly or spark plug), stop using the vehicle immediately! This is a sign of piston or connecting rod failure, which can lead to engine jam.

The service can also offer:

• 🔬 Endoscopy of the cylinder (visual inspection without disassembly).
• 📊 Diagnostics using ECU logs (analysis of parameters in real time).
• 🔧 Leak test (pressure testing of cylinders with compressed air).

Preventing error P0303 on Nissan

To avoid future misfires, follow these tips:

• 🔧 Change candles every 30–40 thousand km (even if they look normal).
• ⛽ Refuel at proven gas stations (avoid E85 and low-quality 92 gasoline).
• 🛢️ Monitor the oil level and change it every 7–10 thousand km (more often for turbo engines).
• 🔧 Clean the injectors every 50 thousand km.
• 📶 Check errors regularly with a scanner (even if CHECK ENGINE does not light up).

On Nissan with timing chain drive (HR16DE, MR20DE) monitor the condition of the chain and shoes - their wear can lead to phase failure and skips. Recommended replacement interval: 150–200 thousand km.

For owners Nissan with LPG: Misfires often occur due to:

• 🔥 Incorrect settings of gas equipment (mixture too lean).
• 🔧 Wear of spark plugs (on gas they last 1.5–2 times less).
• 🛢️ Gas filter clogged.

Solution: adjusting LPG on a stand every 10 thousand km and using spark plugs platinum or iridium electrodes.

FAQ: Frequently asked questions about error code P0303 on Nissan

Is it possible to drive with P0303?

Short term - yes, but not recommended. Long-term driving with misfires leads to:

• 🔥 Overheating of the catalyst and its destruction (repair ~20-40 thousand rubles).
• 🛢️ Increased wear of the piston group.
• ⛽ Increased fuel consumption by 15–30%.

If the error appears for the first time, you can drive to the service center, but do not load the engine (do not exceed 3000 rpm).

Why does error P0303 only appear when it is hot?

This is a typical sign:

• 🔧 Ignition coil breakdown (when heated, the insulation loses its properties).
• 🔧 Air leak through widening cracks in the reservoir.
• 🔧 Oxygen sensor malfunctions (on a hot engine it may give incorrect readings).

Check the coils and pipes for cracks, and also clean the sensor contacts.

I reset the P0303 error, but it comes back. What to do?

If the error appears again, it means that the cause has not been eliminated. Follow the algorithm: