Power Steering Inspection Failures: UK Guide

A properly functioning power steering system is not just about comfort; it's a critical safety component of your vehicle. In the UK, during a routine MOT test or a pre-purchase inspection, the power steering system is thoroughly checked to ensure it meets safety standards. A failure in this area can lead to significant inconvenience, expense, and, most importantly, compromise your safety on the road. Understanding the common culprits behind power steering inspection failures can help you identify potential issues early and prevent them from becoming major headaches.

The power steering system assists the driver in turning the wheels with minimal effort, making manoeuvres like parking or navigating tight corners much easier. When this system malfunctions, it can suddenly become incredibly difficult to steer, especially at low speeds, posing a serious risk. Inspectors are trained to spot even subtle signs of wear or damage that could indicate an impending failure or an immediate safety concern. Let's delve into the specific issues that most frequently lead to a failing grade during a power steering check.

Common Causes of Power Steering Inspection Failure

1. Low or Contaminated Power Steering Fluid

One of the simplest yet most common reasons for a power steering system to fail an inspection is insufficient or degraded fluid. The power steering fluid is the lifeblood of hydraulic systems, transmitting pressure to assist steering. If the fluid level drops too low, often due to a leak elsewhere in the system, the pump can cavitate, leading to a whining noise and reduced assistance. Similarly, if the fluid becomes contaminated with debris or breaks down over time due to excessive heat, it loses its lubricating and hydraulic properties, causing increased wear on components and affecting performance.

• Symptoms: Whining noise when turning, stiff steering, fluid reservoir looks low or discoloured.
• Inspector's Check: Visual inspection of fluid level and condition, checking for recommended fluid type.

2. Leaks in the Power Steering System

Leaks are perhaps the most prevalent cause of power steering issues and a definite inspection failure point. The system operates under high pressure, and any compromise to the integrity of its components can lead to fluid loss. Leaks can originate from several points:

• Power Steering Pump Seals: Over time, the seals within the pump can wear out, allowing fluid to seep out.
• Hoses and Lines: High-pressure hoses can crack, fray, or develop pinhole leaks due to age, heat exposure, or rubbing against other components. Low-pressure return lines can also leak.
• Steering Rack or Gearbox Seals: Internal or external seals on the steering rack (or gearbox in older vehicles) can fail, leading to leaks that might not always be visible but can deplete fluid levels quickly.
• Reservoir Leaks: Cracks in the plastic reservoir or faulty O-rings where hoses connect can also be sources of leaks.

Any visible sign of a leak, no matter how small, will be flagged by an inspector as it indicates a system compromise and potential for further fluid loss, leading to complete system failure.

3. Worn or Faulty Power Steering Pump

The power steering pump is responsible for generating the hydraulic pressure required for assistance. Like any mechanical component, it can wear out over time. Internal components such as vanes, rotors, or bearings can degrade, leading to reduced efficiency or complete failure. A failing pump might still provide some assistance but will often be noisy or inconsistent.

• Symptoms: Loud whining, groaning, or squealing noises that intensify with steering input; steering becomes heavy or inconsistent.
• Inspector's Check: Listening for unusual noises, checking for leaks around the pump, evaluating steering effort.

4. Issues with the Power Steering Hoses and Lines

Beyond simple leaks, the hoses and lines themselves can become problematic. They can become kinked, blocked, or internally deteriorated. A kinked hose can restrict fluid flow, reducing power assistance. Internal degradation can lead to blockages or even burst hoses under pressure. Inspectors will visually check the condition of all accessible hoses for cracks, bulges, or signs of wear.

5. Problems with the Steering Rack or Gearbox

The steering rack (or gearbox in older models) is the central component that translates the steering wheel's rotation into wheel movement. Within the rack, there are seals and pistons that utilise the hydraulic pressure from the pump. If these internal seals fail, fluid can leak internally from one chamber to another, leading to reduced assistance or even a complete loss of power steering without any visible external leaks. Excessive play in the steering rack bushings or tie rod ends connected to the rack can also be a failure point, although this relates more to overall steering play than specifically power assistance.

6. Belt Problems (for Hydraulic Systems)

In hydraulic power steering systems, the pump is typically driven by a serpentine belt or a dedicated power steering belt from the engine's crankshaft. If this belt is loose, worn, cracked, or broken, the pump will not receive the necessary power to operate effectively. A slipping belt will often cause a squealing noise, especially when turning the wheel. A broken belt means no power steering at all.

• Symptoms: Squealing noise from the engine bay, very heavy steering, visible damage to the belt.
• Inspector's Check: Visual inspection of the belt's condition and tension.

7. Electrical System Faults (Electric Power Steering - EPS)

Many modern vehicles are equipped with Electric Power Steering (EPS) systems, which use an electric motor instead of a hydraulic pump. These systems are more energy-efficient but have their own set of potential failure points:

• Motor Failure: The electric motor itself can fail, leading to a complete loss of power assistance.
• Sensor Malfunctions: EPS systems rely on various sensors (e.g., torque sensor on the steering column, wheel speed sensors) to determine how much assistance is needed. A faulty sensor can lead to intermittent or complete loss of power steering.
• ECU (Electronic Control Unit) Issues: The dedicated ECU for the EPS system can malfunction, leading to communication errors or incorrect commands to the motor.
• Wiring or Connector Problems: Damaged wiring or corroded connectors can disrupt the electrical signals, causing the system to fail.

Unlike hydraulic systems, EPS failures often trigger a warning light on the dashboard, which is an immediate red flag during an inspection.

8. Dashboard Warning Lights

Perhaps the most straightforward reason for an inspection failure related to power steering is an illuminated power steering warning light on the dashboard. This light indicates a fault within the system, whether hydraulic or electric. An inspector will immediately note this, and it almost always results in a fail until the underlying issue is diagnosed and rectified, and the light is off.

Hydraulic vs. Electric Power Steering: Common Failure Points Comparison

While both systems aim to achieve the same goal, their common failure points differ significantly:

Preventative Maintenance to Avoid Failure

Regular maintenance is key to preventing power steering issues and ensuring your vehicle passes its inspection:

• Check Fluid Levels Regularly: For hydraulic systems, check the power steering fluid level as part of your routine under-bonnet checks. Top up if necessary with the correct fluid type specified by your car's manufacturer.
• Inspect for Leaks: Periodically look for signs of fluid leaks under the car or around power steering components. A damp patch or a small puddle is a warning sign.
• Listen for Unusual Noises: Pay attention to any new or unusual noises when turning the steering wheel, especially squealing, whining, or groaning sounds.
• Check Drive Belt Condition: For hydraulic systems, inspect the power steering pump's drive belt for cracks, fraying, or excessive looseness.
• Address Warning Lights Promptly: If a power steering warning light illuminates, have it diagnosed by a qualified mechanic without delay.
• Fluid Flushes: Some manufacturers recommend periodic power steering fluid flushes for hydraulic systems. Consult your vehicle's service schedule.

Frequently Asked Questions About Power Steering Failures

Q1: Can I drive my car if the power steering has failed?

While it's technically possible to drive, it is highly inadvisable and potentially dangerous. Steering will become extremely heavy, especially at low speeds, requiring significant effort. This greatly increases the risk of an accident, particularly in emergency manoeuvres. It's best to have the vehicle towed or repaired immediately.

Q2: How much does it cost to fix a power steering failure?

The cost varies significantly depending on the cause. A simple fluid top-up might be inexpensive, but replacing a power steering pump, steering rack, or an EPS motor can be very costly, ranging from a few hundred to over a thousand pounds, including parts and labour. Diagnosis is crucial to determine the exact repair needed.

Q3: Is a power steering warning light an automatic MOT failure?

Yes, if the power steering warning light is illuminated and indicates a fault, it will result in an MOT failure. The system must be fully operational and fault-free for the vehicle to pass.

Q4: How often should power steering fluid be changed?

Unlike engine oil, power steering fluid doesn't always have a strict replacement interval. Many manufacturers consider it a 'lifetime' fluid. However, for optimum performance and longevity, especially in older vehicles or those with high mileage, a fluid flush every 50,000-75,000 miles or every 5-7 years is often recommended by mechanics, particularly if the fluid appears dark or smells burnt.

Q5: Can I use any power steering fluid in my car?

Absolutely not. Power steering fluid types vary significantly (e.g., ATF, synthetic, mineral-based). Using the wrong type can cause serious damage to your system's seals and components. Always refer to your car's owner's manual or a reputable mechanic to ensure you use the correct specification fluid.

Ensuring your power steering system is in top condition is vital for both your safety and the longevity of your vehicle. By being aware of these common failure points and performing regular, simple checks, you can significantly reduce the likelihood of a power steering related inspection failure and enjoy a safer, smoother driving experience. Don't ignore any signs of trouble; addressing minor issues promptly can save you from more extensive and expensive repairs down the line.

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