Squealing or grinding brakes — what's the difference?

A high-pitched squeal at low speed is typically the wear indicator or glazed pads. A grinding or metal-on-metal noise means the pads are worn through — stop driving and replace pads (and likely rotors) immediately.

What is the timing belt replacement cost in Australia?

A timing belt service typically costs $700–$1,200 in Australia on inline engines and more on harder-to-reach layouts. Follow the manufacturer's interval and replace the water pump while it's apart.

Car Diagnostics & Maintenance Guide — AutoBrain | Symptom Checker, OBD2 Codes & Costs

Q: What does the check engine light mean?

A steady check engine light means the engine computer has stored a trouble code — it could be anything from a loose fuel cap to a failed sensor. If the light is flashing, stop driving and get it looked at: that signals a misfire serious enough to damage the catalytic converter.

Q: Car won't start but battery is fine — what's wrong?

A rapid clicking noise with a good battery usually points to a failing starter, corroded terminals or a poor earth. If the engine cranks but won't fire, suspect fuel delivery, ignition (spark), a crankshaft sensor or the immobiliser.

Q: Why does my car shake at 60 km/h?

A vibration that shows up around highway speed is most often wheel balance or alignment, but warped brake rotors, worn CV joints or a driveshaft problem can also cause it.

Q: Why does my car shake when braking?

A pulsing or shaking brake pedal usually means warped or unevenly worn brake rotors. They can often be machined, or replaced if too thin.

Q: Car vibrates at idle — what causes it?

An idle vibration is commonly worn engine or transmission mounts, a vacuum leak, dirty spark plugs or a misfire. It's worth scanning for codes even when no warning light is on.

Q: What does P0300 mean?

P0300 is a generic OBD2 code for random/multiple cylinder misfire. Common causes are worn spark plugs or ignition coils, a vacuum leak, or low fuel pressure. Start with plugs and coils, then scan live data.

Q: What is the P0420 code and how do I fix it?

P0420 means the catalytic converter is operating below the efficiency threshold. Common causes are a failing oxygen sensor, exhaust leaks, or a tired converter itself — test before replacing expensive parts.

Q: How much does an OBD2 diagnostic scan cost in Australia?

A basic OBD2 code scan typically costs $50–$150 at an Australian workshop, and many mechanics waive the fee if you proceed with the repair. You can read many codes yourself with an affordable OBD2 Bluetooth adapter.

Q: What does an alternator replacement cost in Australia?

Alternator replacement generally runs $400–$900 including parts and labour in Australia, depending on the vehicle. Reconditioned units cost less than new ones.

Check engine light is on

Steady light: the engine computer has stored a diagnostic trouble code (DTC). Causes range from a loose fuel cap to a failed sensor. Scan the code before guessing — a $30 OBD2 Bluetooth adapter reads it at home.

Flashing light: this signals a misfire serious enough to damage the catalytic converter. Pull over and don't drive far.

Log the code, symptoms and date in AutoBrain so a repeated fault shows up as a trend instead of a mystery.

Car won't start

Clicking noise, battery fine: likely the starter motor, corroded terminals or a bad earth connection.
Cranks but won't start: no fuel, no spark, a crankshaft or camshaft sensor fault, or the immobiliser.
Won't crank at all: check the battery voltage, terminals, and the battery itself first.

Car shaking, vibrating or vibrating when braking

Shakes around 60 km/h: wheel balance or alignment; worn CV joints or a driveshaft fault.
Shakes when braking: warped or unevenly worn brake rotors — machine or replace them.
Vibrates at idle: worn engine/transmission mounts, vacuum leak, worn plugs or a misfire.

Brakes squealing or grinding

A squeal at low speed is usually the pad wear indicator or glazed pads — near the end of pad life. A grind is metal-on-metal: the pads are worn through and rubbing on the rotor. Grinding brakes need pads (and likely rotors) replaced before further driving.

Car overheating or engine temperature high

Check the coolant level when cool, the radiator cap, thermostat, water pump and cooling fan. If the needle climbs: pull over, shut the engine off, and wait for it to cool before opening the coolant cap — hot coolant under pressure can cause serious burns. Record the overheating incident and the fix in your service log before it turns into a head-gasket failure.

Rough idle and engine misfire

Rough idling is often worn spark plugs, failing ignition coils, a vacuum leak, or dirty fuel injectors. Scan for a misfire code and check live data. Starting with plugs and coils is the cheapest first step for most cars.

Common OBD2 codes explained

P0300 — random/multiple cylinder misfire. Check plugs, coils, vacuum leaks and fuel pressure before throwing parts at it.

P0420 — catalyst system efficiency below threshold. Test the O2 sensor and check for exhaust leaks before replacing the catalytic converter.

Full OBD2 code lists are built into AutoBrain's AI diagnostics: paste the code or describe the symptom and get likely causes, severity, parts and a cost estimate.

Typical repair costs in Australia

Alternator replacement: $400–$900 (parts + labour).
Brake pad replacement (VIC): $200–$450 per axle; plus $150–$400 per axle if rotors are machined or replaced.
Timing belt service: $700–$1,200 on inline engines, more on awkward layouts.
Car diagnostic / OBD2 scan: $50–$150 at a workshop; often waived with a repair.
Logbook service: roughly $200–$400 for common Japanese cars; premium brands cost more.

Indicative only — always get a written quote. AutoBrain tracks what you actually pay so your next repair estimate is based on your own history, not a guess.

OBD2 apps & tracking

AutoBrain is a car maintenance tracker and digital logbook app built for Australian owners: GPS-trip logbook, vehicle service history, parts inventory, resale estimates and rego lookup — on web, mobile and self-hosted. A custom OBD2 port with live fault-code capture, auto-sleep and Bluetooth is in development.

Try the demo — free

Diagnostics FAQ

What does the check engine light mean?

A steady light means a stored trouble code — from a loose fuel cap to a failed sensor. A flashing light means a misfire that can damage the catalytic converter: stop driving.

Car won't start but battery is fine — what's wrong?

Clicking with a good battery points to the starter, terminals or earth. Cranking but no fire points to fuel, spark, a crank sensor or the immobiliser.

Why does my car shake at 60 km/h?

Usually wheel balance or alignment; also warped rotors, worn CV joints or a driveshaft fault.

Why does my car shake when braking?

Warped or unevenly worn rotors — machine or replace them.

Car vibrates at idle — what causes it?

Worn engine mounts, a vacuum leak, worn plugs or a misfire. Scan for codes even without a warning light.

What does P0300 mean?

Random/multiple cylinder misfire. Check plugs, coils, vacuum leaks and fuel pressure first.

What is the P0420 code and how do I fix it?

Catalyst efficiency below threshold. Test O2 sensors and exhaust leaks before replacing the converter.

How much does an OBD2 diagnostic scan cost in Australia?

$50–$150 at a workshop, often waived with a repair. A Bluetooth OBD2 adapter reads codes at home.

What does an alternator replacement cost in Australia?

Typically $400–$900 including parts and labour, depending on the vehicle.

How much does brake pad replacement cost in Victoria?

$200–$450 per axle incl. pads and labour; add $150–$400 per axle for rotors.

What does a logbook service cost in Australia?

Roughly $200–$400 for common Japanese cars; more on premium brands. Independent workshops keep your logbook stamped for less than dealers.

Is there a free app to track car maintenance and logbook?

AutoBrain has a free hosted tier and is MIT-licensed open source — self-host it free. Covers service history, logbook, fuel and diagnostics.

Also read: Car Dashboard Warning Lights — What They Mean & What to Do

Car diagnostics & maintenance guide