Audi S5 Coupe: Clicking Noise & Won’t Start
Everything you need to know — causes, diagnosis, types of clicking, repair costs, DIY fixes & expert answers. The most complete guide online.
📋 Table of Contents
- What Is the Clicking Noise? (Definition)
- Why Does the Audi S5 Coupe Click and Not Start?
- Types of Clicking Noises
- All Common Causes — Detailed
- Symptoms & Warning Signs
- How to Diagnose: Step-by-Step
- How to Fix the Clicking Noise
- Is It Safe? Advantages & Disadvantages
- Repair Costs
- Prevention Tips
- Related Keywords & Questions
- FAQ
Your Audi S5 Coupe is trying to start… but it can’t.
Let’s find out exactly why.
❓ Why Does the Audi S5 Coupe Click and Not Start?
The Audi S5 Coupe starting system consists of several key components: the battery, alternator, starter motor, starter solenoid, battery cables, ground straps, and the Engine Control Module (ECM). When you attempt to start the car, a high current of electricity must flow from the battery to the starter motor to spin the engine flywheel and begin combustion.
When the Audi S5 Coupe makes clicking noise but won’t start, it means:
- Insufficient current is reaching the starter motor
- The starter motor or solenoid has failed mechanically
- There is high resistance in the electrical circuit (corrosion, loose connections)
- The battery cannot hold or deliver the required amperage
- A ground strap or cable is broken or disconnected
Understanding why the Audi S5 Coupe clicks helps pinpoint the exact fix — and this guide covers every single possibility.
🔊 Types of Clicking Noises on Audi S5 Coupe
Not all clicks are the same. The type of clicking sound your Audi S5 Coupe makes is one of the most important diagnostic clues.
Rapid Clicking (Multiple Fast Clicks)
What it sounds like: A fast “click-click-click-click” succession when you turn the key or push start.
What it means: Almost always a dead or severely weak battery. The solenoid fires repeatedly but the battery drops below the voltage needed to spin the starter.
Also called: Machine gun clicking, rapid fire clicking, multiple clicking noise Audi S5.
Single Loud Click (One Click)
What it sounds like: One solid, heavy “CLUNK” or “CLICK” and then nothing.
What it means: Typically a faulty starter motor or bad starter solenoid. The solenoid engages successfully once, but the motor fails to rotate.
Also called: One click no start Audi S5, single click Audi S5 Coupe.
Click + Lights Dim / Go Out
What it sounds like: Click(s) accompanied by dimming or total loss of dashboard and interior lights.
What it means: Completely dead battery, or a major short circuit draining power at the moment of starting.
Intermittent Click (Sometimes Starts)
What it sounds like: Clicks sometimes, starts other times.
What it means: Weak or failing battery that may hold enough charge occasionally, or a corroded terminal making intermittent contact.
🔍 All Common Causes — Detailed
Below are every documented cause of Audi S5 Coupe clicking noise and won’t start, ranked from most to least common.
Dead or Weak Battery — #1 Cause
The single most common reason your Audi S5 Coupe won’t start and clicks is a dead, depleted, or weak battery. The S5 Coupe uses a high-output battery (typically 80–90 Ah) to power its twin-turbo V6 or V8 starter requirements. When the battery falls below approximately 10.5 volts under load, it cannot deliver the 150–250 amps required to spin the starter.
Causes of battery failure: old age (3–5 years), prolonged parasitic drain (leaving lights on), extreme temperatures, frequent short trips that don’t fully recharge the battery, and internal cell failure.
How to identify: Rapid clicking, dim lights, battery warning light on dash, battery more than 4 years old.
Corroded or Loose Battery Terminals
Corroded battery terminals are one of the most overlooked but extremely common causes of Audi S5 Coupe clicking and no start. Even with a fully charged battery, white or green corrosion on the terminal clamps creates high resistance that prevents full current from reaching the starter motor.
How to identify: Visible white/blue-green powder on terminals, intermittent clicking, clicking that goes away when terminals are wiggled, slow engine crank before failure.
DIY Fix: Remove cables, scrub with baking soda and water using a wire brush, dry, reconnect firmly, and apply terminal protector spray.
Faulty Starter Motor
The Audi S5 Coupe starter motor is an electric motor that physically spins the engine flywheel to initiate combustion. Over time (typically 80,000–150,000 miles), the brushes, armature, or solenoid contacts wear out. A bad starter motor on Audi S5 Coupe typically produces one loud single click when the solenoid fires but the motor fails to turn.
Signs of bad Audi S5 starter: Single clunk, grinding noise before failure, intermittent starting, smoke from starter area, starter not disengaging after start.
Bad Alternator (Failed Charging System)
The alternator recharges your battery while the engine runs. A failing alternator on Audi S5 Coupe means the battery slowly depletes over time — you might notice it starts fine in the morning but fails in the afternoon, or after the car has been left for a few days. Eventually the battery gets too low to start the car, causing clicking.
Signs: Battery warning light, dimming lights while driving, radio cutting out, battery dying repeatedly. Alternator output should be 13.8–14.8V with engine running.
Poor Ground Connection
The ground straps and ground cables complete the electrical circuit from the battery negative terminal to the engine block and chassis. A bad ground connection on Audi S5 Coupe causes erratic electrical behavior and prevents sufficient current from flowing through the starter circuit.
How to identify: Multiple electrical glitches alongside no-start, clicking with full battery voltage, interior electronics behaving erratically.
Faulty Starter Relay or Fuse
The starter relay in the fuse box acts as a switch that sends current to the starter solenoid when you turn the ignition. A blown starter fuse or bad relay on Audi S5 will prevent the starter from receiving power at all — you may hear one click from the relay box but the starter will not engage.
Location: Main fuse/relay box under the hood. Check the Audi S5 owner’s manual for the starter relay position.
Seized Engine (Rare)
In rare cases, especially after oil loss or overheating, the engine itself can seize (internal components lock up). A seized engine on Audi S5 will produce a single very loud click as the starter tries to turn a locked engine. This is distinguishable because the starter motor will be fine — but the engine won’t budge manually either.
Warning: This is a severe mechanical failure requiring engine rebuild or replacement.
Battery Drain / Parasitic Draw
A parasitic drain is when an electrical component in the Audi S5 Coupe draws power from the battery when the car is off. Common culprits include a stuck-on interior light, infotainment module staying active, a faulty BCM (Body Control Module), or aftermarket accessories wired incorrectly.
How to test: Use a multimeter in milliamp mode on the negative cable; more than 50mA draw with everything off indicates parasitic drain.
⚠️ Symptoms & Warning Signs
Recognizing the early warning signs of clicking and won’t start on Audi S5 Coupe can save you from being stranded:
| Symptom | Likely Cause | Urgency |
|---|---|---|
| Rapid clicking on start | Dead/weak battery | High |
| Single loud click | Bad starter motor/solenoid | High |
| Dim dashboard lights | Weak or dead battery | High |
| Battery warning light on | Alternator or battery failure | High |
| Slow engine crank before failure | Battery declining — replace soon | Medium |
| Works after jump start | Dead battery (alternator may be bad) | Medium |
| Clicking with all lights on | Battery fully dead, corroded terminals | High |
| Click from under hood fuse box | Bad starter relay | Medium |
| Intermittent starting | Corroded terminals, weak battery | Medium |
| Smoke near starter area | Starter motor overheating/failing | Urgent |
🔬 How to Diagnose: Step-by-Step
Use this systematic diagnostic process for Audi S5 Coupe clicking and no start:
- Check battery voltage: Use a multimeter. Battery should read 12.4–12.8V at rest. Below 12.0V indicates a weak or discharged battery. Below 10V means it is essentially dead.
- Perform a load test: A voltage reading alone isn’t enough. Use a battery load tester or take the battery to an auto parts store for free testing. The battery must hold voltage under load (cranking simulation).
- Inspect battery terminals: Remove the battery cables. Look for white or blue-green corrosion. Check that the clamps are tight — they should not wiggle at all.
- Check all ground connections: Inspect the negative battery cable all the way to the chassis ground point and engine block ground strap. Look for fraying, rust, or loose bolts.
- Jump start test: Connect a known-good jump pack or donor car and attempt to start. If the S5 starts easily, your battery is the problem. If it still only clicks, the starter motor or solenoid is likely faulty.
- Check starter relay and fuse: Locate the starter relay in the fuse box. Swap it with an identical relay from another position to test. Also check the starter fuse with a multimeter or test light.
- Test alternator output: Start the car (if possible) and measure voltage at the battery terminals. Should read 13.8–14.8V. Below 13.5V indicates alternator failure.
- Inspect the starter motor: If all else checks out, have the starter motor bench-tested at a shop or auto parts store. Alternatively, have an Audi technician perform a voltage drop test across the starter circuit.
🛠️ How to Fix the Clicking Noise — All Repair Methods
Fix 1: Jump Start Your Audi S5 Coupe
A jump start is the first thing to try when your Audi S5 Coupe clicks and won’t start:
- Connect the red jumper cable to the positive (+) terminal of your dead battery.
- Connect the other red cable end to the positive (+) of the donor battery.
- Connect the black cable to the negative (–) of the donor battery.
- Connect the final black cable to an unpainted metal ground on your Audi S5 Coupe (not the dead battery negative).
- Start the donor vehicle and let it run for 2–3 minutes.
- Try starting your Audi S5. If it starts, drive for at least 30 minutes to recharge the battery, then test battery health.
Fix 2: Clean or Replace Battery Terminals
If corroded battery terminals are causing the clicking, clean them with a mixture of baking soda and water, scrubbing with a wire brush. Ensure all connections are torqued firmly. Apply dielectric grease or terminal protector spray to prevent future corrosion.
Fix 3: Replace the Battery
If the Audi S5 Coupe battery is over 4–5 years old, or fails load testing, replacement is the correct fix. The Audi S5 Coupe uses an AGM battery. Always replace with an OEM-specification AGM battery and use an Audi-compatible battery registration procedure (coding the new battery to the BCM) to avoid charging system errors.
Fix 4: Replace the Starter Motor
A failed starter motor on Audi S5 Coupe requires replacement. This is typically a 1–3 hour job at a shop. The starter motor is located on the engine block near the transmission bell housing. Access can be restricted on the V6 TFSI model, requiring partial removal of engine covers.
Fix 5: Replace the Alternator
If the Audi S5 Coupe alternator is not charging properly, replace it with a quality OEM or Bosch equivalent. Always replace the serpentine belt at the same time if high mileage.
Fix 6: Repair Ground Connections
Clean and re-torque all ground connection points. If the ground cable is frayed or corroded internally, replace it with a new same-gauge cable. Adding a supplementary ground strap from battery negative to engine block is a reliable upgrade.
Fix 7: Replace Starter Relay
A bad starter relay on Audi S5 is one of the cheapest fixes — typically $10–$30 for the relay itself. Locate the relay in the underhood fuse/relay box and swap for a new one.
🛡️ Is It Safe? Advantages & Disadvantages
No — if the vehicle won’t start, it is not driveable. Attempting to force start can damage the starter motor, drain the battery further, or strain the electrical system. Address the root cause before driving.
✅ Advantages of Addressing This Issue
- Prevents complete vehicle breakdown
- Protects starter motor from burn-out
- Avoids expensive towing costs
- Restores full vehicle reliability
- Can prevent cascading electrical damage
- Maintains Audi S5 resale value
❌ Disadvantages of Ignoring the Issue
- Risk of being stranded in unsafe locations
- Damaged starter motor (costly repair)
- Battery may sulfate if repeatedly discharged
- ECM/BCM may log errors from voltage spikes
- Could indicate deeper electrical issues
- Safety risk if car won’t start in emergencies
💰 Repair Costs — What to Expect
Here are the typical repair costs for Audi S5 Coupe clicking noise and won’t start at an independent shop (US market, 2024):
🛡️ Prevention Tips — How to Avoid Clicking and No-Start
- Test your Audi S5 battery every year, especially before winter — cold temperatures drastically reduce cranking amps.
- Replace the battery every 4–5 years proactively, especially if the S5 sits for extended periods.
- Inspect and clean battery terminals twice a year — spring and fall.
- Drive the S5 regularly — short trips don’t fully charge the battery; use a trickle charger if storing the vehicle.
- Have the alternator output tested when the battery is replaced.
- Keep an OBD2 scanner in the car — early electrical fault codes appear before a no-start condition.
- Never leave accessories running with the engine off for extended periods.
- Use a battery maintainer (like CTEK or Optimate) if the Audi S5 Coupe will sit more than 2 weeks.
🔗 Related Keywords & Questions
People searching about Audi S5 Coupe clicking noise and won’t start also search for:
Common Related Questions
- What does it mean when my Audi S5 Coupe makes a clicking noise?
- How do I know if my Audi S5 Coupe battery is dead?
- Can a bad ground cause clicking noise on Audi S5?
- Why does my Audi S5 Coupe click but has a new battery?
- Is it the starter or battery causing clicking on my Audi S5?
- How much does starter replacement cost for Audi S5 Coupe?
- How do I jump start an Audi S5 Coupe correctly?
- Can clicking damage the Audi S5 starter motor?
- Why does my Audi S5 click more in cold weather?
- Does the Audi S5 need a special battery?
