Can a car not start due to a crankshaft sensor: a complete analysis of the problem

Have you turned the ignition key, but the engine is stubbornly silent or difficult to start? One possible reason is a faulty Crankshaft position sensor (CPS). This small but critical element is responsible for synchronizing the operation of the fuel system and ignition. If it fails, the consequences can range from unstable engine operation to complete failure to start.

In this article, we will look at how exactly the crankshaft sensor affects engine starting, what symptoms indicate its malfunction, and what to do if suspicions fall on it. You will learn how to check the DPKV yourself, what tools you will need for this, and in which cases you cannot do without the help of a car service. We will pay special attention common diagnostic errors, which can mislead even experienced car owners.

It is worth noting that the problem with the crankshaft sensor is relevant for most modern cars - from budget Lada Vesta and Renault Logan up to bonus BMW 5-series and Mercedes E-Class. The principle of operation of the DPKV is universal, but diagnostic nuances may differ depending on the model and type of engine.

How the crankshaft sensor works and why it is important for starting

The crankshaft position sensor (CPS) is the only sensor in the engine management system without which engine cannot be started. Its task is to record the position and rotation speed of the crankshaft, transmitting this data to electronic control unit (ECU). Based on this information, the ECU calculates:

• 🔥 Moment of spark supply to the cylinders (for gasoline engines)
• ⛽ Exact fuel injection time (for diesel and gasoline engines)
• 📊 Ignition timing
• 🔄 Valve timing (in systems with variable phases)

If the DPKV fails or transmits incorrect data, the ECU loses its “reference point” for engine control. In most cases this leads to complete startup failure, since the control unit cannot determine in what position the pistons are and when it is necessary to supply fuel or a spark.

Interestingly, on some cars (for example, Toyota Corolla or Honda Civic) if the DPKV fails, the engine may start, but it will operate extremely unstable - with dips, jerks and spontaneous stops. This is due to the fact that the ECU goes into emergency mode using data from other sensors (for example, the camshaft sensor). However, this mode is not intended for long-term operation and can lead to serious damage.

Signs of a faulty crankshaft sensor: when to sound the alarm

DPKV malfunction manifests itself in different ways, but there are a number of characteristic symptoms that should alert you:

1. The engine won't start at all - the most obvious sign. The starter turns, but the engine does not “catch” or starts and immediately stalls.
2. Unstable idling — the speed “floats”, the engine stalls or stalls for no reason.
3. Loss of power and dips during acceleration — the car jerks, does not respond to the gas pedal or “stumbles” when accelerating.
4. Detonation and popping noises in the exhaust system - arise due to incorrect ignition timing.
5. Check Engine light comes on - the error may indicate DPKV (codes P0335, P0336, P0339 and others).

It is important to understand that these symptoms may indicate other problems, such as problems with the fuel pump, spark plugs, or high-voltage wires. However, if the engine won't start at all, and the starter turns normally, the DPKV becomes one of the main “suspects”.

⚠️ Attention: On diesel engines, a faulty DPKV often results in the engine starting only after several attempts or when towing. This is due to the characteristics of the injection system, where the accuracy of the data from the sensor is critically important.

Symptom	Probability of guilt of DPKV	Other Possible Causes
Engine won't start	⭐⭐⭐⭐⭐	Broken timing belt, faulty starter, lack of fuel
Floating speed	⭐⭐⭐⭐	Air leaks, faulty air flow sensor, dirty injectors
Dips during acceleration	⭐⭐⭐	Malfunction of ignition coils, low fuel pressure
Check Engine Code P0335	⭐⭐⭐⭐⭐	Wiring problems, flywheel ring gear damage

Why the crankshaft sensor breaks: main reasons

DPKV is a reliable element, but it can also fail. Here are the most common reasons:

• 🔌 Mechanical damage — shocks, vibrations or corrosion of the housing (especially important for sensors installed in the lower part of the engine).
• 🔥 Overheating - if the sensor is located near the outlet of the manifold, high temperature can damage its electronic filling.
• 💧 Pollution — metal shavings, dirt or oil falling on the sensitive element distort the signal.
• 🔋 Wiring problems — breaks, short circuit or oxidation of contacts in the connector.
• ⚡ Electrical interference — malfunctions in the on-board network (for example, voltage drops) can damage the sensor.
• ⏳ Natural wear and tear — over time, the magnetic properties of the core weaken, which leads to incorrect readings.

Sensors on cars with high mileage (200+ thousand km) or those that are used in difficult conditions are especially vulnerable - for example, UAZ Patriot or Nissan Patrol, often used for off-road use. Vibrations and shocks reduce the service life of the DPKV.

Another common problem is Damage to the flywheel ring gear or crankshaft pulley. If even one tooth breaks or becomes deformed, the sensor will read incorrect data. This often happens after unsuccessful repairs or an accident.

How to check the crankshaft sensor yourself: step-by-step instructions

Diagnostics of DPKV can be carried out without specialized equipment, using a multimeter or oscilloscope. Here's how to do it:

1. Visual inspection

Start by checking:

• 🔍 Sensor housing integrity - cracks, chips or traces of impacts.
• 🔌 Connector and wiring states - oxidation, breaks or melting.
• 🧲 Sensor purity - metal shavings or dirt at the end.
• 🔗 Flywheel Ring Gear/Pulley - missing or damaged teeth.

2. Checking the winding resistance

Take a multimeter and follow these steps:

Disconnect the sensor connector|Switch the multimeter to resistance measurement mode (200-2000 Ohms)|Connect the probes to the sensor leads (polarity is not important)|Compare the readings with the nominal (usually 500-700 Ohms for inductive sensors)-->

If resistance:

• Significantly higher than normal → winding break.
• Below normal or equal to zero → short circuit.
• Changes when the wire moves → fault in the circuit.

3. Checking inductance (for advanced)

To do this you will need a megohmmeter or an oscilloscope. Algorithm:

1. Connect the probes to the sensor terminals.
2. Measure the inductance (the norm is 200–400 mH).
3. Check the insulation resistance (should be > 20 MΩ).

If you don’t have an oscilloscope, you can use the “old-fashioned” method: with the ignition on, bring a metal object (for example, a screwdriver) to the end of the sensor. If the sensor is working properly, you will hear a slight click or see a reaction on the multimeter.

⚠️ Attention: On some vehicles (for example, Volkswagen Passat B6 or Audi A4) DPKV is integrated into the oil pump housing. Replacing it requires draining the oil and removing the pan - do not attempt this without experience!

What to do if the crankshaft sensor is faulty: repair or replacement

If the diagnostics have confirmed a malfunction of the DPKV, there are two ways:

1. Replacing the sensor

This is the most reliable option. The cost of a new sensor varies from 500 to 5000 rubles, depending on the car model. For example:

• VAZ 2110–2112 — 600–1200 rub.
• Ford Focus 2 — 1500–2500 rub.
• BMW 3-series (E90) — 3000–5000 rub.

The replacement process usually takes 15–30 minutes:

1. Disconnect the negative terminal of the battery.
2. Disconnect the sensor connector.
3. Unscrew the mounting bolt (usually 10 or 12).
4. Remove the old sensor and install the new one, maintaining a gap (usually 0.5–1.5 mm).
5. Tighten the bolt with a force of 8–12 Nm (do not overtighten!).

2. Temporary repair (if replacement is not possible)

In extreme cases, you can try:

• 🧹 Clear sensor from dirt and metal shavings (use alcohol or contact cleaner).
• 🔧 Replace connector - sometimes the problem is in oxidized contacts.
• 📶 Check wire shielding - if it is damaged, the signal may be distorted by interference.

However, remember: DPKV repair is a temporary solution. The sensor operates under extreme conditions, and any “crutches” will sooner or later lead to repeated failure.

1. Integrity of the flywheel/pulley ring gear.

2. Correct installation (gap between sensor and shaft).

3. Condition of the wiring from the sensor to the ECU.-->

Common mistakes when diagnosing DPCV

Many car owners make mistakes that lead to incorrect conclusions. Here are the most common:

• 🔍 Ignoring other sensors - for example, camshaft sensor (DPRV). Their symptoms often overlap.
• ⚡ Checking resistance only — inductive sensors need to be tested comprehensively (resistance + inductance + signal).
• 🔧 Incorrect clearance — if the sensor is installed too close or far from the crown, the signal will be distorted.
• 📉 Diagnostics without errors - if Check Engine does not light up, this does not mean that the DPKV is working properly. On some vehicles, the error appears only when there is a complete failure.
• 🔄 Replacement without inspection — often the sensor is changed “at random”, and the problem lies in the wiring or the ECU.

To avoid mistakes, follow a simple rule: diagnose comprehensively. Check not only DPKV, but also:

• Condition of high-voltage wires and spark plugs.
• Fuel pressure in the rail.
• Starter and battery operation.
• No errors in the ECU (even if Check Engine does not light up).

How to distinguish a faulty DPKV from problems with the fuel system?

If the engine does not start due to DPKV, the starter turns smoothly, but the engine does not “catch” even for a short time. If there is a problem in the fuel system (for example, the fuel pump does not work), when the starter is cranked, you can hear individual “flashes” in the cylinders.

When you can’t do without a car service: difficult cases

There are situations when independent repair is impossible or dangerous:

• 🔧 The sensor is integrated into the oil pump housing (as on some Volkswagen or Audi). Replacement requires draining the oil and special tools.
• 📊 ECU adaptation required - after replacing the sensor on some cars (for example, BMW or Mercedes) “training” of the control unit is required.
• ⚡ Wiring problems — if the harness from the DPKV to the ECU is damaged, you will need a soldering iron and experience working with auto electricians.
• 🔍 Diagnostics with an oscilloscope — For accurate signal analysis you need professional tools.
• 🚗 Warranty car - independent intervention may void your warranty.

If you are not confident in your abilities, it is better to contact the service. The average cost of diagnosing CPCV in Moscow and the regions is 500–1500 rubles. Replacing the sensor will cost 1000–3000 rubles (depending on the complexity of access).

⚠️ Attention: On vehicles with the system Start-Stop (for example, Skoda Octavia or Hyundai Solaric) a faulty DPKV can lead to system failure and permanent engine malfunctions. In this case, you cannot delay repairs!

FAQ: Frequently asked questions about the crankshaft sensor

Can the car start without a crankshaft sensor?

No, on most modern cars the engine will not start without a signal from the DPKV. The exception is old carburetor engines without electronic control, but there is simply no crankshaft sensor.

Which crankshaft sensor is better to choose: original or analogue?

Original sensors are more reliable, but more expensive. If your budget is limited, choose analogues from trusted brands: Bosch, Valeo, Hella or ERA. Avoid cheap no-name spare parts - they often fail after 10-20 thousand km.

Is it possible to drive with a faulty DPKV?

If the engine still starts, you can drive, but it is extremely undesirable. A faulty sensor leads to:

• Increased fuel consumption (up to 20–30%).
• Engine overheating due to incorrect ignition angle.
• Accelerated wear of the catalyst and lambda probes.

We recommend that you fix the problem as soon as possible.

Why does the car still not start after replacing the DPKV?

Possible reasons:

• Incorrect installation (too large or small gap).
• The flywheel ring gear is damaged.
• Problems with wiring or ECU.
• The new sensor is faulty (defective or counterfeit).

Check all circuit elements and repeat the diagnosis.

How often should the crankshaft sensor be replaced?

DPKV is a non-consumable element and has no replacement regulations. It is replaced only when it breaks. However, on cars with mileage of more than 200 thousand km, it is recommended to check the sensor at every maintenance, as the risk of its failure increases.