Symptom
Hard starting
The engine takes longer than usual to fire — extended cranking, several attempts, or starting only when the throttle is used. Worth noting whether it happens cold, hot, or both, because that distinction narrows the cause substantially.
Also described as: difficult to start, slow to start, long crank, takes ages to start, cranks a long time, hard to start, won't start easily, سخت روشن میشود, دیر روشن میشود, سخت استارت میخورد, cuesta arrancar, tarda en arrancar, arranca con dificultad, hay que insistir para arrancar, no arranca en frio, cuesta arrancar en frio, صعوبة في التشغيل, تتأخر بالدوران, تعبان يشتغل, ما تدور من أول مرة, صعوبة التشغيل على البارد, تدور بعد محاولة
Some causes mean you should stop driving
58 of the 201 codes that produce this symptom indicate a fault where continuing to drive risks damage or is unsafe. If the symptom is sudden or severe, treat it as one of those until a scan says otherwise.
What this usually means
Whether it is hard cold, hard hot, or hard after standing is most of the diagnosis, and it is the one thing the driver already knows. The three patterns have different mechanisms and barely overlap.
Hard after standing, easy again once it has run, is a fuel pressure problem and specifically a holding problem rather than a delivery one. German workshop references describe the test directly: after the pump stops, a check valve in the delivery unit is supposed to keep the system near pressure for a manufacturer-specified period. If the gauge falls away quickly, the rail is empty by morning and the management has to rebuild pressure before injection works properly — which is exactly what the extended crank is. A leaking check valve, a weeping injector or a failed pressure regulator all produce it, and only a hold test tells them apart.
Hard cold points at the mixture being wrong for a cold engine. On a diesel that is the glow plug circuit. On a petrol engine it is more often a coolant temperature sensor reading warmer than the engine is, so the management enriches too little and the engine will not catch — a fault which produces no driveability complaint at all once warm, and therefore gets blamed on the battery for months. Hard hot is the opposite population: heat-soaked sensors, vapour in the fuel line, or a starter whose windings have grown resistive with temperature.
One thing to rule out before any of it, because it is free: an engine that needs the throttle held to start is telling you it is being given too little air or too much fuel at idle, which is a different question from a weak spark.
Working through it
| What you find | Likely cause | How to confirm it | What fixes it |
|---|---|---|---|
| Long crank only after standing overnight, normal all day afterwards | Residual fuel pressure bleeding away — a leaking check valve, injector or pressure regulator | Fit a gauge and run a hold test: pressure should stay near its working figure for the manufacturer's stated period after the pump stops. Clamping the supply and return in turn localises which of the three is leaking. | Renew whichever the clamp test names — pump delivery unit, the leaking injector, or the regulator. |
| Hard only from cold, on a petrol engine, with no other complaint | Coolant temperature sensor reading warmer than the engine actually is, so the cold enrichment is too small | Compare the sensor's live reading against a genuinely cold engine and against ambient temperature — they should agree after a night's stand. A sensor that reads 40 °C on a frosty morning is the fault. | Renew the coolant temperature sensor. Check its connector for green corrosion at the same time. |
| Hard only from cold, on a diesel | Glow plug circuit — plugs, relay or control module | Measure each plug's resistance and compare across the set; confirm the relay energises for the pre-heat period. One dead plug in four often only shows in hard frost. | Renew as a set, with the relay or module where that is the failure. |
| Hard only when hot, easy from cold | Heat-affected crank position sensor, vapour in the fuel line, or a starter drawing more current as it heats | Reproduce it hot rather than guessing: watch live engine speed during a hot crank, and measure cranking current and voltage drop with the engine at temperature. | Renew the sensor or starter on the hot-test finding. Insulate or reroute a fuel line only where heat soak is demonstrated. |
| Slow, laboured cranking in any condition | Supply rather than mixture — a tired battery, poor terminals, or a corroded earth strap | Battery voltage under crank should hold above roughly 9.6 V at room temperature, and total voltage drop across the starter feed should stay under about 0.5 V. | Remake the connections first, then the battery on a conductance test. This is not a fuelling fault and fuelling parts will not improve it. |
| Starts only if the throttle is held open | Idle air path blocked or leaking, or an idle control valve stuck — the engine cannot get a startable mixture on its own | Inspect the throttle body and idle passage for carbon, and check the idle control valve moves. Smoke-test for an induction leak downstream of the meter. | Clean the throttle body and idle passage, renew the valve if it is seized, and repair any leak found. |
| Became hard shortly after a fuel fill | Contaminated or wrong fuel, or water in the fuel | Draw a sample and look at it. Water separates and sits at the bottom; the wrong fuel usually reveals itself by the receipt and the timing. | Drain and refill. Renew the filter, and on a diesel check for injection system damage before dismissing it. |
-
Long crank only after standing overnight, normal all day afterwards
- Likely cause
- Residual fuel pressure bleeding away — a leaking check valve, injector or pressure regulator
- How to confirm it
- Fit a gauge and run a hold test: pressure should stay near its working figure for the manufacturer's stated period after the pump stops. Clamping the supply and return in turn localises which of the three is leaking.
- What fixes it
- Renew whichever the clamp test names — pump delivery unit, the leaking injector, or the regulator.
-
Hard only from cold, on a petrol engine, with no other complaint
- Likely cause
- Coolant temperature sensor reading warmer than the engine actually is, so the cold enrichment is too small
- How to confirm it
- Compare the sensor's live reading against a genuinely cold engine and against ambient temperature — they should agree after a night's stand. A sensor that reads 40 °C on a frosty morning is the fault.
- What fixes it
- Renew the coolant temperature sensor. Check its connector for green corrosion at the same time.
-
Hard only from cold, on a diesel
- Likely cause
- Glow plug circuit — plugs, relay or control module
- How to confirm it
- Measure each plug's resistance and compare across the set; confirm the relay energises for the pre-heat period. One dead plug in four often only shows in hard frost.
- What fixes it
- Renew as a set, with the relay or module where that is the failure.
-
Hard only when hot, easy from cold
- Likely cause
- Heat-affected crank position sensor, vapour in the fuel line, or a starter drawing more current as it heats
- How to confirm it
- Reproduce it hot rather than guessing: watch live engine speed during a hot crank, and measure cranking current and voltage drop with the engine at temperature.
- What fixes it
- Renew the sensor or starter on the hot-test finding. Insulate or reroute a fuel line only where heat soak is demonstrated.
-
Slow, laboured cranking in any condition
- Likely cause
- Supply rather than mixture — a tired battery, poor terminals, or a corroded earth strap
- How to confirm it
- Battery voltage under crank should hold above roughly 9.6 V at room temperature, and total voltage drop across the starter feed should stay under about 0.5 V.
- What fixes it
- Remake the connections first, then the battery on a conductance test. This is not a fuelling fault and fuelling parts will not improve it.
-
Starts only if the throttle is held open
- Likely cause
- Idle air path blocked or leaking, or an idle control valve stuck — the engine cannot get a startable mixture on its own
- How to confirm it
- Inspect the throttle body and idle passage for carbon, and check the idle control valve moves. Smoke-test for an induction leak downstream of the meter.
- What fixes it
- Clean the throttle body and idle passage, renew the valve if it is seized, and repair any leak found.
-
Became hard shortly after a fuel fill
- Likely cause
- Contaminated or wrong fuel, or water in the fuel
- How to confirm it
- Draw a sample and look at it. Water separates and sits at the bottom; the wrong fuel usually reveals itself by the receipt and the timing.
- What fixes it
- Drain and refill. Renew the filter, and on a diesel check for injection system damage before dismissing it.
Codes that produce this symptom (201)
Listed with the codes that most typically present this way first — the likeliest place to start.
- P0002 Fuel Volume Regulator A Control Circuit Range/Performance Typical of this code Stop driving High
- P0016 Crankshaft Position — Camshaft Position Correlation (Bank 1 Sensor A) Typical of this code Stop driving High
- P0017 Crankshaft Position — Camshaft Position Correlation (Bank 1 Sensor B) Typical of this code Stop driving High
- P0018 Crankshaft Position — Camshaft Position Correlation (Bank 2 Sensor A) Typical of this code Stop driving High
- P0019 Crankshaft Position — Camshaft Position Correlation (Bank 2 Sensor B) Typical of this code Stop driving High
- P0087 Fuel Rail/System Pressure — Too Low Bank 1 Typical of this code Stop driving High
- P0089 Fuel Pressure Regulator A Performance Typical of this code High
- P008A Low Pressure Fuel System Pressure - Too Low Typical of this code High
- P0090 Fuel Pressure Regulator A Control Circuit/Open Typical of this code Stop driving High
- P0091 Fuel Pressure Regulator A Control Circuit Low Typical of this code Stop driving High
- P0092 Fuel Pressure Regulator A Control Circuit High Typical of this code Stop driving High
- P0094 Fuel System Leak Detected — Small Leak Typical of this code Stop driving High
- P00C6 Fuel Rail Pressure Too Low - Engine Cranking Bank 1 Typical of this code High
- P0115 Engine Coolant Temperature Sensor 1 Circuit Typical of this code High
- P0190 Fuel Rail Pressure Sensor Circuit Bank 1 Typical of this code Stop driving High
- P0191 Fuel Rail Pressure Sensor Circuit Range/Performance Bank 1 Typical of this code Stop driving High
- P0200 Injector Circuit/Open Typical of this code Stop driving High
- P0213 Cold Start Injector 1 Typical of this code Moderate
- P0214 Cold Start Injector 2 Typical of this code Moderate
- P0231 Fuel Pump Secondary Circuit Low Typical of this code Stop driving High
- P0233 Fuel Pump Secondary Circuit Intermittent Typical of this code Stop driving High
- P0251 Injection Pump Fuel Metering Control A — Cam/Rotor/Injector Typical of this code Stop driving High
- P0253 Injection Pump Fuel Metering Control A Low (Cam/Rotor/Injector) Typical of this code Stop driving High
- P0254 Injection Pump Fuel Metering Control A High (Cam/Rotor/Injector) Typical of this code Stop driving High
- P0256 Injection Pump Fuel Metering Control B (Cam/Rotor/Injector) Typical of this code Stop driving High
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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