Audi A5 Sportback Clicking Noise & Won’t Start
Everything you need to know: causes, symptoms, types of clicks, how to fix it, costs, safety, advantages, disadvantages, and expert FAQs — covering all Audi A5 Sportback model years.
Why Does the Audi A5 Sportback Click and Not Start?
The clicking occurs because the starter motor’s solenoid — a magnetic switch that engages the starter pinion with the engine flywheel — is receiving just enough electrical current to activate, but not enough to sustain the cranking action. The solenoid snaps in, draws a heavy current load, the voltage collapses, the solenoid drops out, voltage recovers slightly, it snaps in again — creating the characteristic rapid clicking cycle.
In the case of a single loud click, the solenoid engages fully but the starter motor itself cannot turn (due to a mechanical fault, seized engine, or dead short), or the current path is disrupted immediately.
Types of Clicking Noise on Audi A5 Sportback
Understanding what type of click your Audi A5 Sportback makes is the first step toward a correct diagnosis. There are four distinct patterns, each pointing to a different root cause:
| Click Type | Sound Description | Most Likely Cause | Urgency |
|---|---|---|---|
| Rapid / Rapid-Fire Clicking | Click-click-click-click (5–20+ times) | Weak / discharged battery; corroded terminals | 🟠 High |
| Single Loud Click | One heavy “clunk” or “thud” | Bad starter motor; seized engine; open circuit | 🔴 Very High |
| Clicking + Dashboard Flicker | Clicks with lights dimming/flickering | Low battery voltage; bad ground connection | 🟠 High |
| Clicking + No Dashboard Lights | Click with completely dark dash | Completely dead battery; blown main fuse | 🔴 Very High |
| Clicking from Engine Bay Only | Mechanical knock/click near starter | Starter solenoid stuck; loose starter bolts | 🟡 Moderate |
All Causes of Clicking Noise & No-Start on Audi A5 Sportback
1. Dead or Weak Battery
The most common cause (responsible for 60–70% of all clicking no-start cases). The 12V battery does not hold enough charge to deliver the 200–500 amps required to crank the engine. AGM batteries used in Audi A5 models (especially B9 generation) can fail without warning.
2. Corroded or Loose Battery Terminals
Corrosion on battery terminals (white/blue powder buildup) creates resistance in the circuit, dramatically reducing current delivery. Even a new battery will cause clicking if the terminals are corroded or not tightened properly.
3. Faulty Starter Motor
The starter motor itself can fail due to worn brushes, a burned armature, or a seized motor bearing. This typically produces one loud click (solenoid engaging) with no subsequent cranking. Common on high-mileage Audi A5 Sportbacks over 100,000 km.
4. Defective Starter Solenoid
The solenoid is the electromagnetic switch that connects battery power to the starter motor and mechanically engages the pinion gear. A worn or burnt solenoid may click but fail to complete the circuit or fully engage the gear.
5. Bad Alternator (Prior Failure)
While the alternator doesn’t cause immediate clicking, a failed alternator from a previous drive means the battery was never recharged. The next start attempt finds the battery depleted, producing clicking. Check for a battery warning light that came on during the last drive.
6. Poor Ground Connection
Ground cable faults — between battery negative, engine block, and body — cause high resistance in the return path of the circuit. This is especially common after bodywork repairs or on older vehicles where ground straps have corroded.
7. Anti-Theft / Immobiliser Fault
The Audi A5 Sportback uses an engine immobiliser (EWS system). If the system does not recognise the key, it cuts power to the starter circuit, sometimes producing a clicking relay noise in the fuse box. A fault code will be stored in the ECU.
8. Seized / Hydrolocked Engine
Rare but serious: if the engine is mechanically seized (due to oil starvation or water ingestion), the starter motor cannot turn it. The solenoid will click but the starter pinion cannot engage or rotate the flywheel. Do NOT keep trying to start — you risk burning out the starter.
9. Blown Fuse or Relay
The starter relay and associated fuses in the Audi A5 fuse box (located under the dashboard or in the engine bay) can fail. A blown starter relay will produce relay-clicking sounds without actual starter engagement.
10. ECU / BCM Communication Fault
The Engine Control Unit (ECU) or Body Control Module (BCM) must authorise the start sequence. Electrical gremlins or software faults can prevent the start signal from reaching the starter relay, sometimes accompanied by unusual clicking from the relay bank.
Symptoms of Audi A5 Sportback Clicking No-Start
- Turn key or press start button — only a clicking sound occurs
- Dashboard lights come on but engine does not crank
- Dashboard lights flicker or dim rhythmically with each click
- All electrical accessories work normally (radio, windows) but car won’t start
- Battery warning light was illuminated during recent driving
- Car started fine previously but sat unused for several days or weeks
- Cold weather (below 5°C) makes the problem worse
- Clicking is coming specifically from the engine bay (near starter)
- Clicking comes from the fuse/relay box under the dashboard
- Car starts after jump-starting, confirming battery as the issue
- Car does NOT start even after jump-starting, suggesting starter or engine fault
- Key fob battery low warning displayed on MMI screen
How to Diagnose the Clicking Noise on Audi A5 Sportback
Test Battery Voltage
Use a multimeter to measure battery voltage. A healthy, fully charged 12V battery reads 12.6–12.8V at rest. Below 12.0V indicates a weak battery. Below 11.5V = effectively dead. An AGM battery should hold 12.8V+ when healthy.
Inspect Battery Terminals
Look for white or blue-green powder (corrosion) on the terminals. Check that both clamps are tight — you should not be able to wiggle them by hand. Clean with a mixture of baking soda and water, then rinse and dry.
Attempt a Jump Start
Connect a known-good battery or jump pack. If the car starts immediately after jump-starting, the battery is the confirmed culprit. If it still only clicks after jump-starting, the issue lies with the starter motor or engine.
Load-Test the Battery
A battery load test (done at most auto parts stores for free) applies a simulated engine-start load to the battery and measures voltage drop. A battery that drops below 9.6V under load should be replaced even if it reads 12.6V at rest.
Check Ground Cables
Inspect the negative battery cable running to the engine block and the body ground strap. Look for cracks, corrosion, or loose bolts. A voltage drop test across ground cables can identify a failing ground without visual signs.
Test the Starter Motor Directly
With the battery confirmed good, use a remote starter switch or have a helper turn the ignition while you tap the starter motor body lightly with a rubber mallet. If it suddenly cranks, the motor has worn brushes. This is a temporary fix — replacement is needed.
Check Fuses and Starter Relay
Consult your Audi A5 Sportback owner’s manual for the starter relay location (typically relay position 102 in the engine bay fuse box). Swap with an identical relay from another position to test. Check associated fuses (usually F43 or F47 depending on model year).
Scan for Fault Codes with VCDS / OBD-II
Connect a VCDS (VAG-COM Diagnostic System) or compatible OBD-II scanner to the port under the dashboard. Fault codes in the Engine, BCM, or Immobiliser modules can pinpoint electrical faults that a multimeter cannot detect.
Battery Charge Level Indicator
How to Fix Audi A5 Sportback Clicking Noise & Won’t Start
Fix 1: Jump-Start the Car (Immediate Solution)
A jump-start is the quickest way to get back on the road if the battery is the cause. Connect jump leads correctly: red (positive) to positive terminal, black (negative) to an unpainted metal point on the engine block or chassis (never to the negative battery terminal directly on Audi A5 B9 models — risk of computer damage). Start the donor vehicle, wait 2 minutes, then try starting your Audi.
Fix 2: Replace the Battery
If the battery fails a load test or is more than 4–5 years old, replacement is the correct solution. The Audi A5 Sportback B8 typically uses a 70Ah / 760A CCA battery, while the B9 with Start-Stop requires a 70Ah AGM battery specifically. After replacement on B9 models, the battery must be registered with the car’s BCM using VCDS or a dealer scan tool — failure to do this causes premature battery failure and charging faults.
Fix 3: Clean or Replace Battery Terminals
Mix 1 tablespoon baking soda with 1 cup warm water. Disconnect the battery (negative first), apply the solution to corroded terminals with an old toothbrush, scrub, rinse with clean water, and dry. Apply petroleum jelly or terminal protector spray before reconnecting. If terminals are cracked or the cable is damaged, the entire cable assembly must be replaced.
Fix 4: Replace the Starter Motor
Starter motor replacement on the Audi A5 Sportback is a moderate-to-difficult DIY job. The starter is typically located on the lower front of the engine, near the transmission bell housing. Access varies by engine variant (2.0 TFSI, 3.0 TDI, etc.). Remanufactured starters from quality brands (Bosch, Valeo, Denso) are reliable and cost less than OEM. Labour time: 1.5–4 hours depending on engine.
Fix 5: Replace the Starter Relay
A faulty starter relay is a cheap and easy fix (cost: £5–£20 for the relay). Identify the correct relay position from your owner’s manual or fuse box diagram (printed on the inside of the fuse box cover). Swap the relay with an identical one from a non-critical circuit to test before buying a new one.
Fix 6: Repair or Replace Ground Cables
Ground cable repair involves cleaning ground strap contact points with sandpaper or a wire brush until bare metal shows, then tightening the connections to specification (typically 20–25 Nm). If the cable is frayed, corroded internally, or has a melted sheath, it must be replaced entirely.
Fix 7: Immobiliser / Key Issues
If fault codes indicate an immobiliser fault (fault code 01176 or similar), options include: replacing the key fob battery (CR2032), coding a new key using VCDS, or dealer reprogramming. On rare occasions the Simos/Bosch ECU itself requires coding or replacement.
Repair Costs for Audi A5 Sportback Clicking No-Start
| Repair | DIY Cost | Independent Garage | Audi Dealer |
|---|---|---|---|
| Battery Replacement (AGM) | £80–£180 | £150–£280 | £220–£450 |
| Starter Motor (Remanufactured) | £80–£160 (parts) | £280–£550 | £500–£900 |
| Starter Motor (OEM Bosch) | £180–£350 (parts) | £380–£700 | £650–£1,200 |
| Battery Terminal Cleaning | £0–£5 | £30–£60 | £50–£100 |
| Ground Cable Replacement | £15–£50 | £80–£180 | £120–£300 |
| Starter Relay | £5–£20 | £40–£80 | £60–£120 |
| Alternator Replacement | £150–£300 (parts) | £400–£750 | £700–£1,300 |
| ECU / BCM Fault Diagnosis | £0 (with VCDS) | £60–£120 | £100–£200 |
| Battery Registration (VCDS) | £0 (with VCDS) | £30–£60 | £60–£120 |
Is It Safe to Drive an Audi A5 Sportback With a Clicking No-Start Problem?
The direct answer is: if the car won’t start, you cannot drive it. However, understanding safety context is important for what to do next:
✅ Safe / Lower Risk Situations
- Car starts after jump-starting — safe to drive to a garage immediately
- Only battery issue confirmed — safe to drive once battery is replaced
- Key fob battery dead — replace battery, no driving risk
- Starter relay fault — car safe once relay replaced
- Terminal corrosion — safe to drive once cleaned and reconnected
⛔ Unsafe / Do Not Drive Situations
- Engine seized or hydrolocked — do NOT attempt to start
- Burnt smell or smoke from starter — indicates short circuit
- Alternator failed — battery will die while driving
- Main wiring loom damage visible — fire risk
- Oil pressure warning before no-start — engine damage likely
Advantages & Disadvantages of DIY vs Professional Repair
✅ Advantages of DIY Repair
- Significant cost savings (often 50–70% less than dealer)
- Immediate action — no waiting for appointment
- Learning experience — understand your own car
- Battery and terminal cleaning are beginner-level tasks
- Parts freely available online (Febi, Bosch, LuK)
- VCDS scan tool available from Audi clubs at low cost
⚠️ Disadvantages of DIY Repair
- Risk of incorrect diagnosis wasting money on wrong parts
- Battery registration required on B9 models — needs scan tool
- Starter motor access difficult on 3.0 TDI and TFSI models
- Warranty void if incorrect parts used
- Electrical errors can damage expensive Audi ECUs
- No guarantee if problem recurs
✅ Advantages of Professional Repair
- Correct diagnosis first time using factory tools
- Battery registration done properly
- Parts and labour warranty (usually 12 months)
- Access to Audi Technical Information System (ETKA/ELSA)
- Multi-point inspection may catch other issues
⚠️ Disadvantages of Professional Repair
- Significantly higher cost, especially at Audi dealers
- Wait times for appointments
- Risk of unnecessary upselling of parts
- Car may need recovery if it won’t start at home
How to Prevent Audi A5 Sportback Clicking No-Start Problems
- Have the battery tested every 2 years and replaced proactively every 4–5 years
- Use a CTEK or similar smart battery maintainer if car is stored or rarely used
- Regularly clean battery terminals with a wire brush and apply terminal protector
- If the battery warning light appears, address the alternator immediately — do not ignore it
- Avoid leaving accessories (lights, radio) on with the engine off for extended periods
- In cold climates, switch to a battery with higher Cold Cranking Amps (CCA) rating
- Inspect ground straps during every service — especially after bodywork
- Keep a quality jump pack in the boot for emergencies (e.g., NOCO Genius Boost)
- Annual diagnostic scan with VCDS to catch fault codes before they cause no-starts
- Replace the key fob battery annually (CR2032) — a dead key fob triggers immobiliser faults
Audi A5 Sportback Model-Specific Clicking Issues
Audi A5 Sportback B8 (2007–2016)
The B8 generation uses a conventional lead-acid or EFB (Enhanced Flooded Battery). The 2.0 TFSI engine’s starter motor is accessible from underneath and is a common failure point after 120,000 km. Ground strap issues between the battery and engine block are frequently reported on the B8 platform. The 3.0 TDI variant has a particularly awkward starter location requiring subframe drop in some cases.
Audi A5 Sportback B9 (2016–Present)
The B9 generation introduces a Start-Stop system that mandates AGM battery technology — fitting a standard lead-acid battery will cause faults and premature battery death. The battery is now located in the boot (trunk) on most variants rather than under the bonnet. A critical difference: battery replacement on all B9 models requires ECU registration via VCDS or dealer. The 45 TFSI and 40 TDI engines are generally reliable starters but the 48V mild-hybrid system in later facelifted models adds complexity.
More Related Questions About Audi A5 Sportback Clicking & No-Start
What does it mean when my Audi A5 clicks once and won’t start?
A single click when attempting to start the Audi A5 Sportback almost always indicates either a faulty starter motor (the solenoid engages but the motor cannot turn), a severely discharged battery with just enough charge for one solenoid activation, or a mechanical engine seizure. It rules out a simple weak battery (which typically causes rapid clicking).
Why does my Audi A5 Sportback click rapidly but all lights work?
When the interior and exterior lights work normally but the engine produces rapid clicking, it means there is sufficient battery voltage for low-draw accessories but not for the high-current demand of the starter motor. This confirms a weak (not dead) battery, or a high-resistance connection (corrosion) that collapses under starter load. The battery needs testing and likely replacement.
How long does an Audi A5 Sportback battery last?
Under normal conditions, the 12V AGM battery in an Audi A5 Sportback lasts 4–6 years. However, frequent short journeys (where the alternator cannot fully recharge the battery), extreme temperatures, and regular Start-Stop operation accelerate degradation. Batteries in urban-driven cars or those with many electrical accessories often need replacement at 3–4 years.
Can cold weather cause Audi A5 Sportback to click and not start?
Yes, absolutely. Cold temperatures reduce battery capacity by up to 40% and increase engine oil viscosity, making the engine harder to crank. A battery that performs acceptably in summer may completely fail to start the car on a winter morning below 0°C. If clicking only occurs in cold weather, the battery is on its last legs and should be replaced before winter.
Is the Audi A5 Sportback prone to battery issues?
The Audi A5 Sportback has higher-than-average electrical demands due to its Audi MMI infotainment system, dual-zone climate control, LED lighting, and Start-Stop system. This places more demand on the battery than simpler vehicles. The B9 generation’s AGM battery requirement also means that incorrect battery selection leads to rapid failure. Battery issues are the most commonly reported no-start cause in Audi A5 Sportback owner forums.
What is the Audi A5 Sportback starter motor location?
On the 2.0 TFSI (TFSI/CWGB engine), the starter motor is mounted on the lower left side of the engine, bolted to the transmission bell housing, accessible from underneath. On the 3.0 TDI, the starter is at the rear of the engine and requires partial subframe removal for access. On B9 models, the location is similar but with additional wiring harness management needed due to the 48V system.
Quick-Reference Diagnostic Checklist
- Rapid clicking (5+ times)? → Start with battery voltage test
- Single loud click? → Test starter motor; check for seized engine
- Clicking + dim dashboard? → Low battery voltage; bad ground
- No dash lights + clicking? → Dead battery or blown main fuse
- Jump-start works? → Replace battery; check alternator
- Jump-start doesn’t work? → Starter motor fault; seized engine
- Immobiliser warning on dash? → Key fob battery; ECU fault code
- Battery warning was on last drive? → Alternator failure; replace alternator + battery
- Car sat unused 2+ weeks? → Battery self-discharge; charge fully first
- Recent bodywork or battery replacement? → Check grounds; B9 needs battery registration
Frequently Asked Questions (FAQ)
The clicking noise occurs because the starter motor solenoid is receiving power but either the battery cannot deliver enough sustained current to crank the engine, or the starter motor itself is faulty. Rapid clicking = weak battery. Single click = starter motor issue or seized engine. The most common cause overall is a discharged or failing 12V battery.
Yes, jump-starting is generally safe if performed correctly. Connect positive to positive and negative to an engine ground point (not the battery negative directly, especially on B9 models). Wait 2 minutes after connecting, then attempt to start. If the car starts, drive directly to a garage. If it still clicks after a proper jump start, the starter motor is the likely culprit.
Costs vary by cause: Battery replacement: £80–£450 depending on DIY vs dealer. Starter motor: £280–£1,200 including labour. Terminal cleaning: free to £60. Ground cable: £15–£300. Starter relay: £5–£120. The most cost-effective approach is diagnosing the exact cause first before purchasing parts.
Rapid clicking (multiple clicks per second) almost always means the battery is weak or discharged. The solenoid has just enough power to activate, pulls heavy current, voltage collapses, solenoid releases, and the cycle repeats rapidly. It can also indicate corroded terminals creating resistance. Try a jump-start — if the car fires up immediately, replace the battery.
Not recommended. A car that clicks before starting is experiencing a deteriorating battery or starter motor. If the battery gets you moving today, it may not start the car tonight or tomorrow. Drive directly to a mechanic or auto parts store for battery testing. Do not rely on a vehicle in this condition for long journeys or remote locations.
Yes, absolutely. The B9 generation (2016+) Audi A5 Sportback uses an intelligent battery monitoring system (BMS). When a new battery is fitted, the BCM must be informed of the new battery’s specifications via coding (battery registration). Without registration, the alternator will overcharge the new battery, shortening its life dramatically. Use VCDS, OBD Eleven, or ask the fitting garage to perform battery registration.
The B8 generation (2007–2016) typically uses a 70Ah 760A CCA conventional lead-acid or EFB battery. The B9 generation (2016+) with Start-Stop requires a 70Ah AGM (Absorbent Glass Mat) battery — this is non-negotiable. Using a standard lead-acid battery in a Start-Stop vehicle will cause rapid battery failure and charging system warning lights within weeks.
On B8 models, the battery is located under the bonnet on the right-hand side (passenger side in UK-spec cars). On most B9 models, the 12V battery is repositioned to the boot (trunk) under the floor or behind a side panel. This is a common point of confusion — always check both locations before assuming the battery is inaccessible. There are jump-start terminals in the engine bay on B9 models for convenience.
This is a classic sign of a battery nearing the end of its service life. Cold temperatures reduce battery capacity and increase engine oil viscosity, both increasing the demand on the battery. A failing battery may have adequate capacity at 20°C but insufficient capacity at 0°C or below. The battery passes at room temperature but fails in the cold. Replace the battery before winter to avoid being stranded.
Signs of a failed starter motor on Audi A5 Sportback include: single loud click with no cranking; grinding or whirring sound followed by no engine cranking; car cranks very slowly then stops; starter engages intermittently; burning smell from the starter area. Confirm by jump-starting with a fully charged battery — if you still get a single click or no crank, the starter is the confirmed fault.
