Car systems
Steering and suspension: how they work and what fails
The steering points the front wheels and the suspension keeps them on the ground while soaking up bumps; ball joints, wheels and tires complete the picture. Their faults show up more in the steering wheel and in noises than in the check engine light, and many leave no code.
Reviewed by Daniel Morales, founder of Reprorace SL, on
How it works
Almost every current car has electric power steering: a motor on the column or the rack assists according to the speed and the torque a sensor measures, and a steering angle sensor also reports to the stability control. Older cars use a hydraulic pump driven by the belt.
Springs and shock absorbers carry the car and damp its bounce; control arms, ball joints, bushings and links guide it. The tire pressure monitoring system (TPMS) measures the pressure with sensors in the valves or estimates it with the ABS sensors, and warns you if a tire loses air.
The most common faults
- Electric power steering: it switches off because of low voltage or a torque sensor fault: the steering suddenly becomes heavy.
- Ball joints, links and bushings: clunks over bumps, play in the steering wheel and uneven tire wear.
- Shock absorbers: the car bounces, leans in corners and brakes worse; sometimes you can see oil leaking.
- Alignment and balancing: the car pulls to one side or the steering wheel shakes at certain speeds.
- Tire pressure sensors: a dead battery or a wheel changed without being registered: the light stays on with the right pressure.
A guide, most likely first: a repair shop confirms the diagnosis of each car with its own data.
Symptoms that can come from this system
Tire pressure warning light on: what to do
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Noise when turning the steering wheel: what a click or a creak means
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Car pulls to one side: causes and what to do
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Heavy steering or steering warning light on: what to do
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Clunking noise over bumps: causes and what to do
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Humming noise that rises with speed: wheel bearing or tires
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Steering wheel shakes at a certain speed: what it could be
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ABS or ESP warning light on: what it means and what to do
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Vibration when braking: why the steering wheel or pedal shakes
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The most relevant trouble codes
- C0051Steering wheel position sensor: malfunction
- C0054Steering wheel position sensor signal C: malfunction
- C0526Steering angle sensor module: malfunction
- C0559Power steering control module: range/performance - rear
- C059ARear power steering control module: missing calibration
- C05D6Power steering control module: processor fault
- C0606Steering wheel angle sensor, circuit: signal low
- C061CVariable effort steering actuator, control circuit open
- U0126Lost communication with steering angle sensor module
- U0131Lost communication with power steering control module A
Generic OBD-II/EOBD codes; each manufacturer adds its own. The same symptom can come from another system.
Code blocks of this system
Questions and articles about this system
- How often should you run diagnostics on your car?
- Can I diagnose my car myself?
- What do U codes and lost communication (U0100) mean?
Learn more
See what your car is saying, system by system
The ECO-LITE plugs into the OBD port and shows the codes and live data your car publishes on your phone, explained; when needed, you share the session with your repair shop.
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Frequently asked questions
Can I drive if the steering becomes heavy?
Carefully and slowly you can pull over, but you should not carry on: the effort needed changes suddenly. If it comes with the battery light, the problem may be charging.
Why does the car pull to one side?
The most common reasons are uneven tire pressures or the alignment; also a brake caliper that does not release. Start with the pressures.
Do steering faults leave a code?
Electric power steering and the steering angle sensor do store codes (C05xx, U0126, U0131). Worn joints and shock absorbers do not: they are seen with the car on a lift.