How to Tell if Your Electric Power Steering Motor Is Bad

If your electric power steering (EPS) motor is failing, you’ll typically feel a sudden increase in steering effort—often with an EPS or steering-wheel warning light—along with intermittent or total loss of assist, jerky or uneven assist, or unusual electric whine/clunk when you turn the wheel. The quickest way to confirm is to check battery/alternator voltage, scan the EPS module for fault codes, and inspect connectors and wiring at the steering column or rack; persistent motor-circuit or overcurrent/overheat codes, paired with normal system voltage, strongly point to a bad motor.

What the EPS Motor Does and Why Failures Happen

Electric power steering replaces a hydraulic pump with an electric motor that provides assist based on inputs from torque and steering-angle sensors. The motor must deliver high current in short bursts. Failures typically arise from worn brushes or bearings (in serviceable designs), water intrusion, overheated windings, corroded connectors, or internal electronics faults in the motor/drive unit. Low system voltage and poor grounds can mimic motor failure by starving the motor of current.

Common Signs Your EPS Motor Is Failing

The following signs help you distinguish a genuinely weak or failing motor from other steering or electrical issues. Look for patterns and whether symptoms change with electrical load, temperature, or time driven.

• Steering suddenly becomes heavy, often accompanied by an EPS/steering wheel warning light or “Service Power Steering” message.
• Intermittent assist: assist cuts in and out, especially during parking maneuvers or at idle, then returns at speed or after a restart.
• Notchy or jerky assist: the wheel feels like it “steps” instead of moving smoothly, or self-centering is inconsistent.
• Noise tied to steering load: electric whine, grinding, or clunk from the column or rack area only while turning; may be worse when hot.
• Burning smell or hot-metal/electrical odor after low-speed maneuvers, sometimes followed by a temporary shutdown until the unit cools.
• EPS codes stored: motor overcurrent/overtemperature, motor phase/circuit faults, or internal motor drive faults.
• Symptoms persist even when battery and alternator voltage are normal (about 13.8–14.7 V running), reducing the likelihood of a supply issue.

When several of these symptoms occur together—especially a warning light plus heavy steering and relevant fault codes—the motor or its integrated drive electronics is a prime suspect.

How to Tell a Bad Motor from Other EPS Faults

EPS systems are an ecosystem of sensors, wiring, and software. These clues help separate a motor issue from sensor, alignment, or power-supply problems that can feel similar.

• Torque sensor faults: often cause oscillation, uneven assist left vs. right, or assist that surges with tiny inputs; scan data shows erratic torque readings while motor tests may pass.
• Steering angle sensor or calibration issues: usually light the stability/traction lights and can disable assist after an alignment or battery disconnect; motor itself is healthy.
• Low voltage/charging problems: assist fades at idle with lights or HVAC on, improves with RPM; a weak battery or alternator will flag in a charging test.
• Mechanical rack/column issues: clunks over bumps, play, or binding even with the key off point to mechanical wear, not the motor.
• Thermal protection: long, stationary full-lock steering can overheat the unit; assist returns after cool-down, which suggests protection behavior rather than permanent motor damage.

If scan data shows clean sensor inputs and correct calibration, but the module logs motor phase/circuit or overcurrent faults under normal voltage, the motor or its power stage is the likely culprit.

DIY Checks You Can Do Safely

Before replacing expensive parts, these basic checks can clarify whether the motor is the problem or a symptom of a larger electrical issue.

1. Inspect the EPS unit and connectors: Look at the steering column (in-cabin units) or the rack (underhood) for water intrusion, corrosion, loose plugs, chafed wiring, and damaged grounds.
2. Test battery and charging system: With a multimeter, expect ~12.6 V engine off; 13.8–14.7 V running. Turn the wheel at idle and watch for voltage dips below ~12.5 V—if it sags, fix power supply first.
3. Scan the EPS module: Use a scanner that can read manufacturer-specific EPS codes and live data; generic OBD-II often won’t access EPS. Note codes for motor circuit, overcurrent, overheating, or internal failure.
4. Wiggle-test the harness: While idling, gently move the EPS harness and connectors; if assist cuts in/out, suspect wiring or connector faults.
5. Listen carefully while turning: A consistent electric whine or growl that rises with steering effort, especially from the motor body, hints at internal wear.
6. Check for recalls/TSBs: Search your VIN and service bulletins; some models have known EPS connector, water-intrusion, or software issues that mimic motor failure.

These steps often reveal whether a simple electrical or software fix will restore assist, or whether the motor assembly itself is at fault.

What a Professional Will Do to Confirm

If the basics check out but symptoms persist, a technician can run targeted tests to isolate the motor from the rest of the system.

• Bidirectional tests: Commanded EPS self-tests, motor activation, and current draw checks via a factory-level scan tool.
• Live-data correlation: Compare requested torque vs. delivered assist and motor current/temperature during controlled maneuvers.
• Scope testing: Inspect three-phase waveforms to find winding imbalance, commutation faults, or a failing power stage.
• Resistance/insulation checks: Measure motor winding resistance and insulation to detect shorts to ground from water intrusion.

When the motor fails these objective tests with a healthy power supply and valid sensor inputs, replacement or rebuild is typically warranted.

Can You Drive with a Bad EPS Motor?

Most vehicles remain steerable if assist is lost, but effort can become very high at low speeds, which is unsafe. If the EPS warning appears with heavy steering, avoid highway driving, limit speed, and seek service promptly. Stop immediately if you notice burning smells, smoke, grinding that worsens rapidly, or multiple warning lights indicating broader electrical issues.

Repair Options and Typical Costs

Costs vary by vehicle and whether the motor is serviceable separately. Here’s what owners commonly face in 2024–2025 markets.

• Complete rack or column replacement (integrated motor): Parts $900–$2,800; labor $300–$1,200 depending on access and alignment needs.
• Motor-only replacement or reman (where separable): Parts $300–$800; labor varies by access; availability is model-dependent.
• Wiring/ground repairs, fuses/relays: Often $0–$250 if corrosion or loose connections are the root cause.
• Battery/alternator fixes: Quality battery $120–$500; alternator $400–$1,200 installed, which can resolve assist issues caused by low voltage.

Many EPS units require programming or calibration after replacement (torque sensor, steering angle, or ADAS camera/radar alignment). Factor this into quotes and ensure the shop has the required tools.

Prevention and Longevity Tips

While EPS motors are designed to last, a few habits and checks can extend their life and reduce false alarms.

• Maintain a healthy 12 V system: Replace weak batteries early and verify alternator output under load.
• Avoid holding the wheel at full lock: This maximizes current and heat; release slightly after reaching the stop.
• Protect against water intrusion: Keep rack boots intact, ensure cowl drains are clear, and avoid deep standing water.
• Apply software updates: Manufacturer EPS updates can improve thermal management and diagnostics.
• Gentle steering when cold: Allow electronics and grease to warm briefly in very cold weather before heavy maneuvers.

These practices reduce stress on the motor and help prevent heat- or moisture-related failures that often precede permanent damage.

When to Seek Help Immediately

Some scenarios warrant pulling over or visiting a shop without delay to protect your safety and prevent further damage.

• Sudden, sustained spike in steering effort while driving, especially with an EPS warning.
• Multiple warning lights (EPS, battery/charging, ABS/ESC) appearing together.
• Burning smell, smoke, or grinding that escalates during low-speed turns.
• After a curb hit or collision that coincides with new EPS symptoms.

Addressing these red flags early can turn an expensive rack replacement into a simpler wiring fix—or prevent a hazardous situation.

Summary

A bad electric power steering motor reveals itself through heavy or intermittent assist, EPS warnings, and load-dependent noises, especially when system voltage is healthy. Verify basics—battery/alternator output, wiring/grounds, and EPS fault codes—then differentiate motor faults from sensor or calibration issues using scan data. If motor circuit or overcurrent/overheat codes persist with normal voltage, the motor or its integrated driver is likely failing. Prompt diagnosis can keep you safe and may save money by ruling out simpler causes before replacing major components.