Have you ever wondered why modern cars are so easy to drive even at low speeds, unlike older cars where you literally had to force the steering wheel to turn? The secret lies in three letters - EPS. This abbreviation is increasingly found in the technical characteristics of cars, but not all drivers know what it means and how it affects how they control the car.
In this article we will not just decipher EPS, but we’ll also figure out how electric power steering works and why it’s better than hydraulic power steering (power steering), what its pros and cons are, and we will also learn to recognize the first signs of malfunctions. If you are planning to buy a car with EPS or have already encountered problems in its work - this material will help you understand all the nuances.
EPS in the car: decoding and main purpose
EPS (from English Electric Power Steering) is electric power steering. Unlike the classic hydraulic booster (power steering), where the force is created due to fluid pressure, in EPS An electric motor controlled by an electronic unit is responsible for everything. The main task of the system is to facilitate the rotation of the steering wheel, making driving more comfortable and precise.
First serial EPS appeared in the early 2000s on compact city cars (for example, Toyota Yaris or Honda Jazz), but today they are installed even on large crossovers and premium sedans. The reasons for its popularity are simple:
- 🔋 Economical — no pumps, belts or fluids that require maintenance.
- ⚡ Energy efficiency — the amplifier only works when the steering wheel is turned, without constantly taking power away from the engine.
- 🎯 Adaptability - the electronic unit can change the force depending on the speed, driving mode or even weather conditions.
It is important to understand that EPS is not just a “helper” for weak hands. The system is integrated with other vehicle electronic systems such as ESP (stabilization system) or ADAS (driver assistants). For example, in some models EPS can automatically steer when the anti-skid system is activated or keep the car in the lane.
EPS device: what does electric power steering consist of?
Construction EPS simpler than that of a hydraulic booster, but at the same time more technologically advanced. Main components of the system:
- Electric motor - the heart of the system. Can be installed on the steering column, rack or directly on the steering mechanism. Modern cars often use brushless motors, which are quieter and more reliable.
- Control unit (ECU) - "brain" EPS. Analyzes data from sensors and calculates the required force. In some machines this unit is combined with the control unit ESP.
- Torque sensor — determines with what force the driver turns the steering wheel and transmits the data to ECU.
- Steering wheel position sensor — monitors the steering angle.
- Gearbox — transmits force from the engine to the steering mechanism.
Depending on the location of the electric motor, there are three types EPS:
| Type EPS | Where is the motor installed? | Benefits | Disadvantages | Examples of cars |
|---|---|---|---|---|
| Columnar (C-EPS) | On the steering column | Compact, low price | Limited force, not suitable for heavy machines | Kia Rio, Hyundai Solaris |
| Rack and pinion (R-EPS) | On the steering rack | High force, precise feedback | More expensive, more difficult to repair | Volkswagen Golf, Ford Focus |
| Spindle (P-EPS) | On the steering shaft (rarely) | Good balance between compactness and power | Complex design | BMW 3 Series (E90) |
Interestingly, in premium cars (for example, Audi A8 or Mercedes S-Class) can be installed duplicated EPS - with two motors and control units. This is done to increase reliability: if one motor fails, the second will continue to work, albeit with less efficiency.
Why doesn't EPS have hydraulics?
Unlike power steering, where the force is generated by oil pressure, EPS uses an electric motor. This avoids problems with fluid leaks, wear of seals and pumps. In addition, the electrical system distributes force more accurately and can adapt to driving style.
How EPS works: principle of operation and differences from power steering
Work algorithm EPS can be divided into several stages:
- The driver begins to turn the steering wheel, creating torque on the shaft.
- The torque sensor records the force and sends a signal to the control unit.
- ECU analyzes data from other sensors (speed, wheel angle, lateral acceleration) and calculates the required additional force.
- An electric motor helps turn the steering mechanism through a gearbox.
- The system adjusts the force in real time - for example, at high speed the steering wheel becomes “heavier” for safety.
Key difference from power steering — no constant load on the engine. In a hydraulic booster, the pump always works, even when the steering wheel is stationary, taking up to 5–7 hp. power. B EPS the engine turns on only when you turn the steering wheel, which saves fuel (up to 0.3–0.5 liters per 100 km in the urban cycle).
Another advantage - effort variability. For example:
- 🚗 In the parking lot, the steering wheel rotates easily, almost “with one finger.”
- 🏁 On the highway, the force increases so that the driver “feels” the road better.
- ❄️ Some cars have a “Winter” mode, where the force is reduced for smoother maneuvers on slippery surfaces.
However, EPS there are also disadvantages. Main - electronics addiction. If the control unit or sensor fails, the amplifier may turn off completely and the steering wheel will become “oaky”. B power steering if the belt breaks, the pump simply stops pumping fluid, but the steering remains operational (albeit with great effort).
EPS saves fuel and adapts to driving conditions, but is entirely dependent on the health of the electronics. Unlike power steering, if there is a serious breakdown, the steering wheel can become unusually heavy.
Signs of EPS malfunction: when is it time to go for diagnostics
Electric power steering is a reliable system, but it can also break down. The first signs are often ignored until the problem becomes critical. Pay attention to the following symptoms:
- ⚠️ The steering wheel became harder to turn - especially noticeable at low speeds. This may indicate a malfunction of the motor or control unit.
- ⚠️ Extraneous sounds - creaking, humming or knocking when turning the steering wheel. Most often, a worn gearbox or motor bearings are to blame.
- ⚠️ The steering wheel jerks or turns spontaneously - a sign of problems with sensors or electronics.
- ⚠️ The EPS icon on the dashboard lights up (usually a yellow or red steering wheel with an exclamation mark).
- ⚠️ The amplifier is jerky - sometimes it helps, sometimes it “turns off.”
Some faults can be diagnosed independently:
⚠️ Attention! If, when you turn on the ignition, the steering wheel does not “reset” to the neutral position (remains turned), this may indicate a breakdown of the steering angle sensor. Operating the machine in this condition is dangerous - the amplifier can turn off at any time.
More accurate diagnostics are carried out using a scanner connected to the diagnostic connector OBD-II. Common mistakes EPS, which the scanner reads:
C1010— control unit malfunction.C1020— problem with the torque sensor.C1030- open or short circuit in the motor circuit.C1040— low voltage in the on-board network (often associated with the battery).
If the icon on the panel is lit EPS, but the steering wheel works normally, the reason may be a temporary glitch. Try:
Turn the ignition off and on again|Check the battery voltage (must be at least 12.4 V)|Inspect the fuses (usually F30 or F31 in the block)|Try to reset the error with a scanner-->
If after these steps the icon does not go out, professional diagnostics are required. Most often they fail:
- 🔌 Electric motor - wear of brushes or bearings.
- 📱 Control unit - overheating, corrosion of contacts.
- 🔄 Torque sensor — mechanical damage or oxidation.
Repair or replacement of EPS: which is cheaper and more reliable?
Repair cost EPS depends on the nature of the breakdown and the car model. On average prices are as follows:
| Type of work | Cost (RUB) | Deadlines | Notes |
|---|---|---|---|
| Diagnostics with a scanner | 500–1 500 | 30–60 min | Often free of charge if the repair is done in the same service |
| Replacing the torque sensor | 3 000–8 000 | 2–4 hours | The price depends on the car model |
| Control unit repair | 5 000–15 000 | 1–3 days | Sometimes it's cheaper to buy a used unit |
| EPS motor replacement | 10 000–30 000 | 3–5 hours | Premium cars are more expensive |
| Complete replacement of rack with EPS | 25 000–100 000+ | 1 day | The most expensive option |
Main question: repair or change? It all depends on the breakdown:
- ✅ If the sensor or fuse is broken - definitely a renovation. It's cheap and fast.
- ⚠️ If the problem is in the motor or gearbox - repairs are possible, but not always justified. For example, replacing motor brushes will cost 3–5 thousand rubles, and a new motor costs 15–20 thousand rubles.
- ❌ If the control unit fails — it is often cheaper to buy a contract (used) unit than to repair an old one. But here it is important to check compatibility by VIN code.
Please note guarantee. Many services provide a guarantee for repairs. EPS only 3-6 months, whereas a new rail takes 1-2 years. If your car is older than 10 years, sometimes it is more profitable to install a contract rack assembly than to repair the old one.
⚠️ Attention! When replacing EPS must be done steering rack adaptation (reset control unit settings). Without this, the steering wheel may shake or turn spontaneously. In some cars (for example, VW or Audi) adaptation can only be done using a dealer scanner.
If you decide to renovate EPS yourself, please note:
- 🔧 To disassemble the rack, you need a special tool (for example, a steering rod puller).
- 📖 Without a sensor connection diagram, it’s easy to make mistakes during assembly.
- ⚡ Work with electronics requires disconnecting the battery, otherwise you can burn the control unit.
In 80% of cases, EPS malfunctions are associated with oxidation of contacts or wear of motor brushes. Before replacing the entire rack, check these elements - repairs will cost several times less.
How to extend the life of EPS: prevention and care
Electric power steering does not require as frequent maintenance as power steering (where the fluid needs to be changed), but it also needs attention. Here are some tips to help avoid breakdowns:
- 🔋 Keep an eye on your battery. EPS sensitive to voltage sags. If the battery is weak, the amplifier motor may run rough.
- 🚿 Avoid driving through deep puddles. Water getting into the connectors of the control unit or motor leads to corrosion and short circuits.
- 🔄 Do not hold the steering wheel in the extreme position for more than 5 seconds. This puts maximum stress on the motor and can lead to overheating.
- 🛑 Don't hit the steering wheel on the stops (for example, when parking). Shocks are transmitted to the torque sensor and can damage it.
It is also useful to carry out preventive maintenance once a year:
Check the mounting of the motor and rack (there should be no play)|Clean the contacts of the control unit from oxidation|Check fuses and EPS relays|Update the firmware of the control unit (if there are official updates)-->
If you often drive off-road, install crankcase and steering rack protection. This will save EPS from impacts and dirt. In some cars (for example, Toyota RAV4 or Mitsubishi Outlander) the rack is located low and vulnerable to mechanical damage.
For owners of cars with mileage of more than 150 thousand km, it is useful to do steering rack diagnostics. Over time, bushings and seals wear out, which leads to backlash and leakage (in the case of hybrid systems EPS+power steering). The cost of diagnostics is about 1,000–2,000 rubles, but it is cheaper than repairs after a serious breakdown.
If after washing the car the steering wheel becomes harder to turn, most likely water has got into the EPS connectors. Do not turn on the ignition until the contacts are dry - this may burn the control unit.
EPS vs power steering vs electric power steering: which is better to choose
If you are faced with choosing a car and are in doubt which power steering to prefer, let’s compare all three systems:
| Characteristics | EPS (electric) | Power steering (hydro) | EGUR (electrohydro) |
|---|---|---|---|
| Reliability | High (no fluid and pumps) | Average (wear of seals, leaks) | High (hybrid system) |
| Service | Does not require | Fluid replacement every 60–100 thousand km | Fluid replacement every 100 thousand km |
| Economical | Saves fuel (the engine only works when turning) | Constant load on the engine (pump always running) | The pump only turns on when you turn the steering wheel |
| Feedback | Worse (artificial, depends on the firmware) | Better (natural road feel) | Good (combines the advantages of power steering and EPS) |
| Repair cost | Expensive (electronics, control units) | Medium (more often leaks and pump wear) | High (complex hybrid system) |
| System weight | The lightest | Heavy (pump, reservoir, liquid) | Medium |
So which amplifier is better? The answer depends on your priorities:
- 🏙️ For city and compact cars — EPS optimal. It is lightweight, economical and maintenance-free.
- 🚜 For SUVs and heavy vehicles — power steering or EGUR preferable as they provide more force.
- 🏁 For sports cars - many manufacturers are returning to power steering because of better feedback.
Interesting fact: in some modern cars (for example, Tesla Model 3 or BMW i4) EPS integrated with the system Steer-by-Wire, where there is no mechanical connection between the steering wheel and the wheels. Instead, sensors and electric motors are used. Such systems allow the implementation of autopilot functions, but have not yet become widespread due to high prices and safety issues.
FAQ: Frequently asked questions about EPS in cars
Can I drive if the EPS icon comes on?
If the steering wheel rotates, but is heavier than usual, you can go to a service center, but do not delay repairs. If the steering wheel becomes “oaky” or turns spontaneously - operating the machine is dangerous. In some cars (for example, Ford) upon failure EPS The steering column may become blocked.
Why does EPS turn off while driving?
Most often this is due to:
- Discharged battery (voltage below 11.5 V).
- Overheating of the engine (for example, after a long off-road drive).
- Error in the control unit (reflashing required).
After the engine cools down or restarts, the amplifier usually turns on again.
Is it possible to install EPS instead of power steering?
Technically possible, but inappropriate. You will need:
- Replace the steering rack with a model with EPS.
- Reflash the engine control unit (since the load from the pump will disappear power steering).
- Install additional sensors.
The cost of such tuning is comparable to buying a new car. It's much easier to sell a car with power steering and buy a model with EPS.
How to reset EPS error without a scanner?
On some cars (for example, Toyota or Hyundai) you can reset the error by following these steps:
- Turn off the ignition.
- Turn the steering wheel all the way to the left and hold for 5 seconds.
- Turn the steering wheel all the way to the right and hold for 5 seconds.
- Return the steering wheel to neutral position.
- Turn on the ignition.
If the error was temporary (for example, due to a voltage drop), it will be reset. Otherwise, you need a scanner.
What kind of oil should I put in EPS?
B clean EPS oil is not poured in - there are no hydraulics. If you have hybrid system (EGUR), use the fluid recommended by the manufacturer (usually PSF-3 or PSF-4 for Toyota, CHF for Citroen/Peugeot). Do not mix different types of liquids!