For a motorist, winter means not only snowy landscapes and New Year’s mood, but also a daily lottery: "it will start - it won't start". The situation when the starter turns vigorously, and the engine is stubbornly silent, is familiar to many. It would seem that the battery is alive, there is electricity, but the motor shows no signs of life. What's the matter?
The problem lies not in the mechanics of the starter (it works!), but in the chain of systems that must work synchronously to start the engine. Frost complicates everything: the oil thickens, the battery capacity drops, and the fuel evaporates worse. But often it is not only weather conditions that are to blame, but hidden faults, which do not manifest themselves in the summer. Let's figure out where to look for the root of evil and how to bring the car back to life without a tow truck.
1. Discharged battery: when “it turns, but not enough”
The first thing that comes to mind is dead battery. But how does the starter turn? The fact is that to scroll the crankshaft it is enough minimum voltage (about 9–10 V), but for work ECU, injectors and ignition systems you need at least 11.5–12 V. In cold weather, the battery capacity drops by 30–50%, and these “almost 12 volts” may not be enough for stable operation of electronics.
How to check? Turn on high beam or stove on maximum:
- If the light is dim and the starter turns with effort, it’s a battery critically discharged.
- If the light is bright, but the engine does not start, the problem is different (see the following sections).
- 🔋 Quick solution: "light" from another car or use starter charger (not a booster!). Important: observe the polarity and order of connecting the terminals!
- 🔌 Long term solution: check
generator(should produce 13.8–14.4 V at idle), clean the terminals of oxides, replace the battery if it is more than 4–5 years old. - ❄️ Prevention: At night, remove the battery and keep it warm or use thermal case heated.
⚠️ Attention: If after “lighting up” the engine starts, but after 5–10 minutes it stalls and won’t start again, it’s your fault generator, not the battery. A faulty alternator does not charge the battery, and it dies again.
2. Problems with the fuel system: gasoline does not burn, diesel does not ignite
If the battery is ok but the car won't start, it's to blame fuel - either his no, or it does not ignite. In cold weather the problems get worse:
- ⛽ Gasoline engines: fuel evaporates worse, and in old carburetor cars (for example, VAZ 2107 or GAZ 24) condensation may form in the line, blocking the supply of gasoline.
- 🚜 Diesel engines: diesel fuel thickens and turns into “paraffin jelly”, clogging fuel filter and injectors. This is especially true for summer diesel fuel at −15°C and below.
How to diagnose:
- Listen to the work fuel pump (in gasoline cars): when you turn on the ignition, a short hum should be heard for 2-3 seconds. If it is not there, the pump does not pump.
- Check fuel pump fuse (usually F3 or F15 in the fuse box).
- For a diesel engine: if after spending the night in the cold the car does not start, but the starter turns briskly - 100% problem is frozen fuel.
| Sign | Gasoline engine | Diesel engine |
|---|---|---|
| The starter turns, but the engine does not "get enough" | Injectors clogged, no spark, low fuel pressure | Diesel fuel is frozen, glow plugs do not work |
| The engine starts but stalls | Defective Mass air flow sensor or TPDZ |
Air in the fuel system, faulty injection pump |
| Exhaust smells like gasoline/diesel | Fuel overflow (candles flooded) | Fuel does not ignite (problems with glow plugs) |
Solutions:
- For gasoline cars: check fuel rail pressure (norm: 2.5–3.5 bar). If there is no pressure, the pump is at fault or pressure regulator.
- For diesel engines: add antigel into the tank (if the car has not yet stalled) or warm the fuel filter with a hairdryer (not open flame!).
If there is little fuel left in the tank, condensation accumulates faster. In winter, try to keep the gasoline/diesel level above ½ tank.
3. Malfunctions of the ignition system: no spark, or it is weak
If fuel is supplied but the engine does not start, the problem may lie in no spark. In cold weather, this is especially true for gasoline engines, where moisture and cold aggravate problems with:
- 🔥 Spark plugs: if they are old or filled with gasoline (due to an over-rich mixture), the spark will be weak or absent altogether.
- 📶 High voltage wires: microcracks in the insulation lead to spark “leakage” to the ground, especially in wet weather.
- 🔧 Ignition coils: at low temperatures they may malfunction, especially on cars with individual coils (for example, Renault Logan or Kia Rio).
How to check spark:
1. Unscrew the spark plug, insert it into high voltage wire tip.
2. Press the threaded part of the spark plug onto mass (for example, to the cylinder block).
3. Crank the starter: if spark blue and stable — the spark plug is working; if weak or absent - the problem is in the wires, coil or ECU.
⚠️ Attention: On modern cars with ECM (electronic engine management system) unscrewing the spark plugs may cause an error P0300 (misfire). After checking, reset the error with a scanner or by disconnecting the battery terminal for 10 minutes.
Solutions:
- Flooded candles: unscrew them, dry them with a hairdryer or heat them on a gas stove (do not overheat!), then clean them sandblaster or a wire brush.
- Wires and coils: check the resistance of the wires (normal: 3–10 kOhm) and replace if broken. The coils are tested with a multimeter (primary winding resistance: 0.5–2 Ohms, secondary: 6–15 kOhms).
☑️ Ignition system diagnostics
4. Oil pressure and viscosity: when the engine “won’t crank” when cold
If the starter turns, but the engine seems "jammed" - guilty oil. In cold weather it thickens, and it is difficult for the oil pump to pump it through the system. As a result:
- 🛢️ Oil pressure drops to a critical level, and pressure sensor blocks startup (relevant for some foreign cars, for example, BMW or Audi).
- ⚙️ The crankshaft turns with difficulty, and the starter does not have enough power to crank the engine to the required speed.
How to check:
- Look at dashboard: If after turning on the ignition the oil pressure light does not go out for more than 2-3 seconds, the oil is too thick.
- Try starting the engine with clutch depressed (for manual transmission). If the engine starts, the problem is in the oil viscosity or clutch basket.
| Temperature, °C | Recommended oil viscosity | What happens if the oil is not suitable? |
|---|---|---|
| −10...−20 | 0W-30, 0W-40, 5W-30 | The starter turns, but the engine does not start due to high resistance |
| −20...−30 | 0W-20, 0W-30 | Risk of “oil starvation” at startup, accelerated wear of the turbine (on diesel engines) |
| −30 and below | 0W-20 or synthetic with additives | The timing belt may break due to thickened oil (relevant for VW 1.8T, Opel Z18XER) |
Solutions:
- Fill in winter oil with low temperature viscosity (for example, Liqui Moly 0W-20 or Mobil 1 0W-30).
- If the correct oil has already been filled, but the engine does not start, try heat the tray a hair dryer (do not direct hot air at plastic parts!).
- For diesels: check oil filter - if it is clogged, the pump will not be able to pump thick oil.
What to do if the wrong oil has already been filled?
If you fill in oil with a viscosity of 10W-40 or 15W-40, and it is −20°C outside, do not try to start the car head-on. Better to tow it to a warm garage and change the oil. Attempting to start with thick oil may result in rotation of the liners or broken timing belt.
5. Sensors and electronics: when the computer blocks startup
Modern cars are stuffed with sensors, and if at least one of them gives incorrect readings, ECU maybe block launch. The most common failures in cold weather are:
- 🌡️ Coolant temperature sensor (DTOZH): if he lies, the computer incorrectly calculates the composition of the mixture. For example, it shows +20°C when the real one is −15°C - the engine gets a lean mixture and does not start.
- 🔄 Crankshaft position sensor (CPS): when the contacts oxidize or the pulley moves, the signal disappears, and ECU “does not see” what position the pistons are in.
- 💨 Mass air flow sensor (MAF): when frozen or dirty, it produces incorrect data and the engine “chokes.”
How to diagnose:
- Connect diagnostic scanner (for example, ELM327) and check for errors. Codes P0115–P0119 - problems with DTOZH, P0335–P0339 — DPKV malfunction.
- If there is no scanner: turn off the sensors one by one (for example, mass air flow sensor) and try to start the car. If the engine starts, the disconnected sensor is to blame.
Solutions:
- Clean the sensor contacts WD-40 or contact cleaner.
- Check the power supply circuit of the sensors: the ground on the body often oxidizes or the wire breaks.
- For mass air flow sensor: try it ignite (gently heat with a hairdryer) - sometimes this temporarily restores performance.
⚠️ Attention: If the car starts after disconnecting the sensor, do not drive for so long! For example, without mass air flow sensor ECU goes into emergency mode, and fuel consumption will increase by 1.5–2 times.
If the engine does not start, but the indicator light is on on the dashboard immobilizer icon (car with a key), the problem is not in the cold, but in key chip or immobilizer antenna. Try starting with the second key.
6. Immobilizer and alarm: when the electronics “think” that you are a thief
Sometimes the car does not start not because of frost, but because immobilizer or alarm failure. Symptoms:
- The starter turns, but fuel is not supplied (you can’t hear the fuel pump running).
- Flashing on the dashboard immobilizer icon (key or car with an exclamation mark).
- The alarm makes unusual sounds or blocks startup.
Reasons:
- The battery is dead alarm key fob (for example, StarLine or Pandora).
- Crash in key chip (often happens after washing or dropping the key).
- Contacts have oxidized immobilizer antennas (located around the ignition switch).
Solutions:
1. Try starting the car second key.
2. If there is Valet service button (usually hidden under the panel), press it 3-5 times - this will reset the alarm to emergency mode.
3. Check the immobilizer fuse (usually F10 or F20 in the block).
4. If all else fails, have the car towed to an auto electrician for immobilizer flashing.
On some cars (for example, Toyota Corolla or Ford Focus) the immobilizer can be bypassed by placing the key near the antenna (usually near the steering column) and starting the car without the key inserted.
7. Mechanical problems: timing belt, compression, valves
If all the previous steps did not help, the problem may be mechanical. In cold weather, some faults appear more clearly:
- 🔗 Timing Belt/Chain: if it slips by 1-2 teeth, the valve timing is confused and the engine does not start (but the starter turns). In cold weather, the belt can become dull and break.
- 💨 Low compression: If the cylinders are not sealed (rings are worn out, valves are burned out), a cold engine will not be able to create sufficient pressure for ignition.
- 🔧 Stuck valve: possible at sub-zero temperatures hydrocline (antifreeze getting into the cylinder) or rings sticking.
How to diagnose:
- Check compression (norm: 10–14 bar in gasoline engines, 20–30 bar in diesel engines). If the pressure in one cylinder is 25% lower, there is a problem there.
- Inspect the timing belt: if it stretched, cracked or oiled - Replace immediately.
- Listen to the engine while cranking with the starter: metallic knock - a sign of problems with valves or connecting rods.
⚠️ Attention: If you hear when cranking with the starter crunching or grinding, stop immediately! It could be crankshaft bearing failure or broken timing belt. Further attempts to start will result in engine overhaul.
FAQ: Frequently asked questions about starting the engine in cold weather
Is it possible to jump start a car in cold weather?
It is possible, but with reservations:
- ✅ Allowed for gasoline car with manual transmission.
- ❌ Prohibited for diesels (risk of damage to the timing belt) and cars with automatic transmission (the gearbox will fail).
- ⚠️ Do not push the car ice - if she breaks down, you won't be able to stop her.
Do "quick starts" in cans help?
Yes, but this temporary solution:
- 🔥 Effective for gasoline engines, if the problem is poor fuel evaporation.
- ❌ They don’t help if there is no spark or the diesel fuel is frozen.
- ⚠️ Excessive use may damage the catalyst.
Best brands: Liqui Moly Start Fix, Mannol Motor Starter.
Why doesn’t diesel start after spending the night in the cold, but gasoline does?
Diesel fuel begins to thicken at −15°C and turns into a gel at −20°C. Gasoline remains liquid down to −60°C. In addition, to start a diesel engine you need:
- 🔥 Workers glow plugs (heat the combustion chamber).
- ⚙️ Serviceable injection pump (high pressure fuel pump).
- 🛢️ Winter diesel fuel (summer freezes already at −5°C).
What to do if the car starts but immediately stalls?
Causes and solutions:
- 🔋 Dead battery: the generator does not have time to charge the battery. Solution: Let the car idle for 10-15 minutes or recharge the battery.
- ⛽ Airing the fuel system (diesel): Bleed the injection pump with a hand pump (if equipped).
- 🌡️ Faulty DTOZH: The engine is getting the wrong mixture. Solution: Replace the sensor.
How to properly “light” a car in cold weather?
Step by step instructions:
- Connect positive terminals red wire.
- Connect minus donor to recipient weight (for example, to the engine block), and not to the negative terminal!
- Start donor and let it work for 5 minutes.
- Try to have a recipient. If it doesn't work, wait another 5 minutes.
- After launch don't jam engine 15–20 minutes.
Errors: do not “light” from a working donor (risk of voltage surge), do not use thin wires (must be ≥ 16 mm²).