Understand your car. Fix the problem. Know what it should cost.
MotorLogic is an editorial reference for owners. Car problems, warning lights, OBD-II codes, maintenance intervals, and repair costs — sourced, structured, and written for the person paying the bill.
CoveringCar problemsWarning lightsOBD-II codesMaintenanceRepair costs
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Start with what you know
A symptom, a dashboard warning, or the code your scanner returned — any of them opens the right page.
Your vehicle
Look up your make, model and year
Reliability, known issues and maintenance schedule for the car you actually drive.
Spark Plug Replacement Cost — Why Quotes Vary
Two quotes, same car — reconciled
Two quotes, same car — reconciled. The plug materials, the labour hour, the V6 rear-bank access, and the coil-inspection line — laid out so the shop's number becomes legible instead of opaque.
Start here
Common car problems
Diagnose by symptom — what causes it, whether it's safe to drive, and what the fix costs.
Car Shakes When Braking
A shudder felt through the steering wheel or brake pedal when slowing down, usually from uneven rotor thickness.
Read the guide- High
Car Won't Start
No crank, a single click, rapid clicking or endless cranking — each sound points at a different failure and a different repair.
9 min read
- Moderate
Car Battery Keeps Dying
A battery that goes flat repeatedly is one of three things: a battery that no longer holds charge, an alternator that stopped replacing it, or something in the car staying awake overnight.
10 min read
- Critical
Car Overheating
Temperature gauge climbing into the red, steam from under the hood, or a coolant warning — almost always a leak, a stuck thermostat or a fan that stopped working.
10 min read
- Low
Car AC Not Cooling
Air comes out of the vents but it is not cold — nearly always low refrigerant from a leak, a compressor that will not engage, or a blocked airflow path.
9 min read
Dashboard
Warning lights & diagnostic codes
Identify the symbol on your cluster, or look up the code your scanner returned.
- Check Engine Light
- Oil Pressure Warning Light
- Engine Temperature Warning Light
- Brake System Warning Light
- Battery / Charging System Light
- ABS Warning Light
Frequently searched codes
Full code library- P0420ModerateCatalytic Converter Efficiency Low (Bank 1)Catalyst System Efficiency Below Threshold (Bank 1). The engine control module compared the oxygen sensor signals before and after the bank 1 catalytic converter and determined the converter is no longer storing and releasing oxygen well enough to meet the emissions standard the vehicle was certified to.
- P0300HighRandom or Multiple Cylinder MisfireRandom/Multiple Cylinder Misfire Detected. The engine control module has counted combustion failures across more than one cylinder, or misfires it cannot attribute to any single cylinder, based on momentary variations in crankshaft acceleration between firing events.
- P0301HighCylinder 1 MisfireCylinder 1 Misfire Detected. The engine control module has identified repeated combustion failures in cylinder number 1 specifically, measured as a momentary slowdown in crankshaft acceleration at the point in the firing order where that cylinder should have delivered power.
- P0303HighCylinder 3 MisfireCylinder 3 Misfire Detected. The engine control module has counted repeated combustion failures in cylinder number 3, identified by a momentary loss of crankshaft acceleration at that cylinder's position in the firing order.
- P0171ModerateEngine Running Lean (Bank 1)System Too Lean (Bank 1). Long-term fuel trim on bank 1 has reached the maximum positive correction the engine control module is permitted to apply — typically around +25% — meaning the computer has run out of authority to add enough fuel to reach the target air-fuel ratio.
- P0455LowLarge Fuel Vapor (EVAP) System LeakEvaporative Emission Control System Leak Detected (Large Leak). During its leak-detection test the engine control module could not develop or hold the required pressure or vacuum in the sealed fuel vapor system, indicating an opening substantially larger than 0.040 inch — a gross leak.
Stay ahead of it
Maintenance & repair costs
Real intervals, what a shop should charge, and where the DIY line sits.
- Car Maintenance Schedule: What Your Manufacturer Actually Says (And Where They Disagree)There is no single car maintenance schedule. Manufacturers publish intervals for the same service item that differ by four, five and six times over — this page shows the spread instead of averaging it away.Shop cost $1,104–$1,656 per year — AAA's 11.04¢/mile applied at 10,000–15,000 miles driven
- 30,000, 60,000 and 90,000 Mile Service: What You Actually Need (And What the Dealer Adds)Written for the reader holding a service quote. What a manufacturer actually schedules at each of the three thresholds, which items are inspections rather than replacements, and what gets added on top.Shop cost $55–$600 spans a single cabin filter to a full 60,000-mile list — this is not a typical figure
- 100,000-Mile Service: What It Includes, What It Costs, and What You Can SkipPublished estimates for the same 100,000-mile service differ by six to seven times. Here is why, what a manufacturer actually schedules at that mileage, and how to decide what is worth doing.Shop cost $400–$2,800 published estimates for the same service differ six- to sevenfold — this is a spread, not an estimate
- How Often Should You Change Brake Fluid?Published brake fluid intervals run from every 2 years or 20,000 miles at one end to no interval at all at the other. That spread is the answer, and averaging it away is how most sites get this wrong.Shop cost $50–$205 per service
Browse
Popular car models
Reliability, known issues and ownership costs by model year.
- 2021 BMW 3 Series3.0/5Mechanically sound in the way that matters — the B48 and B58 engines and the ZF 8-speed are all well-regarded, and the G20 has no defining defect the way some earlier BMW generations did. The three is about cost, not fragility. Ordinary maintenance items on this car are expensive, several known wear points arrive between 60,000 and 100,000 miles, and BMW-specific procedures mean fewer independent shops can do the work correctly. A well-kept example is a genuinely good car with a genuinely high running cost.5 documented issues · Annual upkeep $1,200–$2,200 per year, maintenance and repairs
- 2021 Chevrolet Equinox3.0/5Middle of the road and priced accordingly. The six-speed automatic, the body and the electrical architecture are all straightforward, but the 1.5L turbo has a real oil consumption pattern across this generation and the A/C condenser is a recurring expense. Nothing here is catastrophic in the way the Escape's coolant intrusion issue is, and a well-maintained example is a perfectly sensible used crossover — it just is not a Toyota.4 documented issues · Annual upkeep $550–$1,000 per year, maintenance and repairs
- 2021 Chevrolet Silverado 15003.0/5Simple, cheap to service and easy to find parts for, with one concentrated and expensive risk in the cylinder deactivation hardware. A Silverado that has had its lifters done, or whose DFM has been disabled, is a considerably better long-term bet than one that has not.5 documented issues · Annual upkeep $700–$1,400 maintenance and repairs per year
- 2021 Ford Escape2.0/5The lowest score here, and it is earned by one issue rather than general shoddiness. The 1.5L EcoBoost coolant intrusion recall covers a large share of 2020–2022 Escapes and the failure mode ranges from a misfire to a destroyed engine. Add a transmission that many owners describe as clumsy and this is a vehicle that needs homework. The hybrid, with a different engine and a much simpler transmission, is a substantially better bet and would score well above this on its own.4 documented issues · Annual upkeep $550–$1,050 per year, maintenance and repairs
- 2021 Ford F-1503.0/5Mechanically sound and easy to service, held back by first-model-year electronics and a transmission that draws more complaints than anything else on the truck. Parts and labor are the cheapest in the full-size segment, which offsets a higher rate of small annoyances.6 documented issues · Annual upkeep $700–$1,300 maintenance and repairs per year
- 2019 Ford F-1503.0/5Structurally excellent and mechanically mixed. The frame, aluminum body and axles hold up to genuine work, and plenty of these trucks pass 200,000 miles. But two of the most-reported issues on this generation — 10-speed transmission shift quality and cam phaser rattle on the 5.0L V8 — are both expensive if they need hardware rather than software, and that keeps the score honest at three. Running costs are also simply higher than a sedan: bigger tires, bigger brakes, more fuel.4 documented issues · Annual upkeep $750–$1,400 per year, maintenance and repairs
What MotorLogic is
Built for people who want to understand their car — not be sold to.
Every page here is written for owners. A shop wants the work, a brand wants the sale, and a lot of auto content is written accordingly. MotorLogic is the opposite: an editorial reference where every price, interval and diagnostic step traces back to a named source.
Independent
No manufacturer, shop, chain or aftermarket-parts affiliation. Nothing on the site changes because a company asks.
Source-cited
Every cost, interval and repair figure cites its source by name — RepairPal, Kelley Blue Book, AAA, BLS and equivalents.
For the owner
Written for the person who has to approve the work, not the person doing it. Every article explains the 'why' before the 'what'.
Reading
Latest guides
Buying advice, comparisons and practical how-tos for everyday owners.
- Diagnostics
What To Do When Your Check Engine Light Comes On
A steady light means read the code within a week. A flashing light means pull over. Here is how to tell the difference and what to do next.
8 min readUpdated August 12, 2026
- Diagnostics
How to Read OBD-II Codes Yourself
Every car sold in the US since 1996 has the same diagnostic port. A $30 reader and ten minutes gets you the same code the shop looks up.
7 min readUpdated July 22, 2026
- Roadside
How to Jump-Start a Car Safely
The order of the four clamps matters, and the last one does not go on the battery. Here is the sequence that keeps sparks away from the vent.
7 min readUpdated June 18, 2026