Nissan Almera G15 won't start: 12 reasons and what the driver should do

Nissan Almera G15 — a reliable sedan, but even it is not immune to problems with engine starting. If your car refuses to start, the reasons may lie in the electrical system, fuel system, or even mechanical problems. In this article we will analyze all possible scenarios, from a banal battery discharge to serious breakdowns ECU or immobilizer, and we will also give step by step instructions for self-diagnosis.

Feature Almera G15 (2013–2019) - sensitivity to fuel and electronics quality. For example, On models with the HR16DE engine, there is often a problem with the crankshaft sensor, which can block starting without errors on the dashboard. We have collected the experience of car owners and service technicians to help you quickly localize the problem and save on diagnostics.

1. Checking the battery: first steps in case of starting failure

Let's start with the most obvious - battery. Even if the lights on the dashboard light up when you turn the ignition key, this does not guarantee that the battery is working. On Almera G15 minimum voltage to start the engine - 11.8 V. At lower values, the starter will “pull” weakly or not respond at all.

How to check:

• 🔋 Multimeter: Connect the probes to the battery terminals (red to “+”, black to “–”). Voltage is lower 12.4 V When the ignition is turned off, the battery is discharged.
• 🔧 Load: Turn on the headlights and radio. If the light dims when you try to start, the battery cannot support the load.
• 🔄 "Lighting up": If the engine starts after connecting to another car, the problem is in your battery.

Please note terminal oxidation — white coating on the contacts increases resistance. Clean them with sandpaper or a special brush. If the battery is older than 4–5 years, its capacity could drop critically, especially in cold weather.

⚠️ Attention: On Almera G15 with the system Start/Stop (if installed) battery discharge to 11.5 V may cause malfunction ECU and require reflashing.

2. Starter: why doesn’t it turn or click?

If you hear when you turn the key single clicks or starter doesn't rotate at all, the problem may be:

• 🔌 Solenoid relay - contact wear or winding breakage.
• 🔗 Wiring — oxidation of the “mass” on the body or an open circuit from the ignition switch.
• ⚙️ Mechanical part — wear of the bendix or jamming of the rotor.

For diagnostics:

1. Check if there is 12 V on the control wire of the solenoid relay (thin wire) when turning the key.
2. If there is voltage, but the starter does not respond, the relay or the starter itself is faulty.
3. Try a “direct” circuit: use a screwdriver to connect the two large contacts on the solenoid relay (be careful - sparking is possible!). If the starter spins, change the relay.

Symptom	Probable Cause	Solution
Clicking sound, but the starter does not turn	Defective solenoid relay	Replacing a relay or starter
Starter turns slowly	Discharged battery or bad ground	Charge the battery, check the contacts
The starter does not respond, the lights do not light up	Open circuit or faulty ignition switch	Check wiring, check fuses

3. Immobilizer and alarm system: why they block the start

On Almera G15 there are often problems with standard immobilizer (system NATS/NATS-5). If the dashboard flashes or stays on red key, The ECU blocks the start. Reasons:

• 🔑 The chip in the key is faulty — a cracked circuit board or a dead battery (in keys with buttons).
• 📡 Immobilizer antenna failure — around the ignition switch. Contacts often oxidize.
• 🖥️ Error in the ECU — flashing or reset of key adaptation is required.

How to bypass the block temporarily:

1. Try the second key (if available).
2. Disable the alarm (if installed) - sometimes it conflicts with the immobilizer.
3. Disconnect the battery terminal for 10 minutes - this may reset the error in the ECU.

⚠️ Attention: If after resetting the terminal the immobilizer continues to block starting, do not try to “deceive” the system by disconnecting the antenna! This will lead to complete blocking of the ECU and will require a visit to the dealer for reflashing.

On some Almera G15 after 2016 the system was installed NATS-5+which requires key adaptation when replacing the ECU or immobilizer. Without this, the engine will not start even with the original key.

How to check the immobilizer antenna?

The antenna is located around the ignition switch. To check it, you need to remove the plastic steering column cover and use a multimeter to test the circuit from the antenna connector to the immobilizer unit (located behind the dashboard). The resistance should be within 1–2 ohms. If the circuit is broken or the resistance tends to infinity, the antenna must be replaced.

4. Fuel system: no gasoline or pressure

If the starter turns, but the engine does not “catch”, the problem may be fuel system. On Almera G15 with engines HR16DE And K4M common faults:

• ⛽ Lack of gasoline in the tank - yes, it sounds banal, but the level sensor can lie.
• 🔧 Faulty fuel pump - does not create pressure (standard: 3.5–4 bar).
• 🛢️ Clogged injectors or filter - especially after refueling with low-quality fuel.
• 🔍 Fuel pressure sensor - may produce false signals to the ECU.

How to check:

1. When you turn on the ignition you should hear buzzing sound fuel pump (2–3 seconds). If it is not there, the pump does not work.
2. Check the pump fuse (F30, 15A in the block under the hood).
3. Measure the pressure in the fuel rail with a pressure gauge (connected to the fitting on the rail).

Symptom	Reason	Action
The starter turns, but the engine does not start	No fuel pressure	Check pump, filter, relay
The engine starts and stalls	The injectors are clogged or the mass air flow sensor is faulty	Cleaning injectors, diagnostics of mass flow sensor
Long startup (you need to turn the starter for a long time)	Low pressure in the rail or air leaks	Check pressure regulator, vacuum hoses

5. Sensors and ECUs: hidden causes of malfunction

Modern engines Almera G15 controlled by an electronic unit (ECU), which relies on sensor readings. If at least one of them produces incorrect data, the ECU may block launch or fuel supply. The most problematic sensors:

• 📊 Crankshaft sensor (CKP) - if it malfunctions, the ECU does not “see” the position of the shaft and does not produce a spark.
• 🌡️ Coolant temperature sensor (ECT) - if it shows -40°C, The ECU enriches the mixture and the engine “floods”.
• 💨 Mass air flow sensor (MAF) — when contaminated, it produces false data, which leads to a lean mixture.

How to diagnose:

1. Connect a diagnostic scanner (for example, ELM327) and check for errors. Codes P0335 (crankshaft sensor) or P0115 (temperature sensor) directly indicate the problem.
2. Check the sensor connectors for oxidation or broken wires.
3. Replace the suspicious sensor with a known good one (for example, from another Almera).

Deserves special attention crankshaft sensor. On HR16DE it is located next to the flywheel and is often contaminated with metal shavings. Cleaning or replacing the sensor solves the problem in 70% of cases of “non-start” without other symptoms.

6. Mechanical faults: timing belt, marks, compression

If all electrical systems are in order, but the engine does not start, the reasons may be mechanical:

• 🔗 Broken timing belt - on HR16DE this leads to bending of the valves (plug-in engine).
• 🔄 Broken timing marks - after replacing the belt or chain.
• 💥 Low compression - worn piston rings or burnt valve.
• 🛢️ Hydraulic compensators - if they “knock”, they can block the camshaft.

How to check:

1. Remove the timing belt cover and check its integrity. If the belt is broken, the engine will not start.
2. Turn the crankshaft with a wrench (by the pulley bolt) and listen for any extraneous sounds (knocking, grinding).
3. Measure the compression in the cylinders (standard: 12–14 bar, spread between cylinders is no more than 1 bar).

⚠️ Attention: If on Almera G15 with engine HR16DE the timing belt broke, don't try to start the car before renovation! This will cause the pistons to hit the valves and cause costly major repairs.

On engines K4M (1.6 l) timing belt is more durable, but also requires replacement every 60,000 km. If you are not sure about the condition of the belt, it is better to check it visually.

7. Algorithm of actions: what to do if Almera does not start

To avoid wasting time, follow this diagnostic procedure:

1. Check the battery - voltage, terminals, ground.
2. Make sure the starter turns - if not, look for a problem in it or the wiring.
3. Listen to the fuel pump - Should buzz when the ignition is turned on.
4. Check immobilizer — whether the light is on or responds to the second key.
5. Diagnose sensors — especially the crankshaft and temperature.
6. Rule out mechanical problems — timing belt, compression.

If a problem is found at any stage, fix it. If everything is in order, but the engine does not start, there are two options left:

• 🔧 ECU diagnostics — perhaps the unit is “buggy” and requires flashing.
• 🚗 Tow truck for service — for deep testing (for example, with an oscilloscope).

Frequently asked questions about Nissan Almera G15

Why does the starter turn, but the engine does not start?

The reasons may be lack of fuel (faulty pump, clogged filter), lack of spark (problems with coils, crankshaft sensor) or mechanical faults (broken timing belt, low compression). Start by checking the fuel pressure and diagnosing errors with a scanner.

How to bypass the immobilizer on Almere G15?

Bypass the standard immobilizer yourself NATS impossible - this will lead to blocking of the ECU. The only legal ways are to use the original key, reflash the ECU at the dealer, or disable the immobilizer programmatically (requires specialized equipment).

What voltage should the battery be to start?

Minimum voltage for reliable starting - 12.4 V with the ignition off and not lower 11.8 V when cranking with the starter. If the voltage is lower, the battery needs to be charged or replaced. In cold weather these values should be higher by 0.2–0.3 V.

Is it possible to start the Almera G15 from a pusher?

Push start Almera G15 with a manual transmission you can, but be careful: on the engine HR16DE if the timing belt breaks, this will lead to bending of the valves. On automatic (CVT) this method of starting is strictly prohibited - the box will fail.

Where is the fuel pump fuse located?

Fuel pump fuse (F30, 15A) is located in the fuse box under the hood (next to the battery). Also check the pump relay (R17) - it may stick or fail.