Power Steering Problems in Modern Electric Steering Systems

Most new cars no longer use a belt-driven pump and hydraulic fluid to help you steer. Instead, they use electric power steering, often called EPS, which relies on a motor, sensors and a computer. EPS is efficient and needs little maintenance, but when it fails, the symptoms and repairs are different from what older drivers may expect.

How electric power steering works

In a hydraulic system, an engine-driven pump pushes fluid to help turn the wheels. In an EPS system, an electric motor does that job. A torque sensor in the steering column measures how hard you are turning the wheel. A control module reads that input, along with vehicle speed and other data, and tells the motor how much help to give.

The motor may be mounted on the steering column, on the steering rack, or on a separate gear that drives the rack. Many systems also feed lane-keeping and parking-assist features, so the steering system is now tied into the car's driver-assist electronics.

Warning signs to watch for

EPS problems can show up suddenly or build gradually. Common signs include:

• A steering warning light or message on the dash
• Steering that suddenly feels heavy, especially at low speeds
• Assist that cuts in and out, or feels uneven from left to right
• The steering wheel not returning to center normally
• Clunking or knocking felt through the wheel
• Lane-keeping or parking-assist features shutting off with a fault message

If steering becomes heavy while driving, slow down carefully and pull over when it is safe. You can still steer without assist, but it takes much more effort.

Common causes

Because EPS is electrical, many problems start with power or signals rather than worn mechanical parts.

1. Low voltage. A weak battery, a failing alternator or poor ground connections can trigger reduced assist. Some systems lower assist on purpose to protect themselves when voltage drops.
2. Torque sensor faults. If the sensor sends bad readings, the module may limit or shut off assist.
3. Motor failure. The assist motor can wear out or overheat.
4. Control module problems. Software glitches or internal failures can cause warnings or loss of assist. Sometimes a software update fixes the issue.
5. Wiring and connectors. Corrosion or loose connectors, especially on rack-mounted units exposed to road spray, can cause intermittent faults.
6. Mechanical wear in the rack. Worn inner joints or a damaged rack can still cause clunks and play, even in an electric system.

What repairs usually involve

Diagnosis usually starts with a scan tool to read stored codes and live data. A good shop will check the battery and charging system before condemning expensive steering parts.

Repairs can range widely:

• A battery replacement, ground cleanup or connector repair is relatively simple.
• A software update or recalibration may be needed after other work, such as an alignment or rack replacement.
• On many vehicles, the motor, sensor and module come as one assembly with the column or rack, so a single failed part can mean replacing a large, costly unit.

After replacing EPS parts, many cars need a steering angle sensor calibration so stability control and driver-assist features work correctly.

Recalls and service bulletins

Manufacturers sometimes issue recalls or technical service bulletins for steering faults. Before paying for a repair, look up your vehicle identification number on the federal recall lookup site run by NHTSA, or ask a dealer to check. A recall repair is done at no charge regardless of warranty status.

Prevention and coverage

EPS needs less maintenance than hydraulic steering, but a few habits help:

• Replace a weak battery before it causes problems.
• Keep the charging system healthy.
• Avoid holding the wheel at full lock for long periods, which can overheat the motor.
• Get clunks and warning lights checked promptly.

Steering components are often included in mid-level and higher service contract tiers. Because EPS combines mechanical and electrical parts, check how a plan lists the rack, motor, sensors and control module. Some plans spell each one out, while exclusionary plans cover anything not listed as excluded.

How Warranty Wizards can help

Warranty Wizards helps you compare plans from third-party providers and explains how each one covers steering parts before you buy. You can request a free quote to see your options.