Car systems
Engine and lubrication: how they work and what fails
The engine turns the combustion of air and fuel into rotation, and lubrication keeps a film of oil between its moving parts so they do not wear out or seize. The most serious faults almost always start with the oil: low pressure, a low level or old oil. If the red oil pressure light comes on, stop the engine as soon as it is safe.
Reviewed by Daniel Morales, founder of Reprorace SL, on
How it works
In each cylinder, the piston moves up and down and turns the crankshaft. The valve train (belt or chain, camshafts and valves) opens and closes the intake and exhaust at the right moment, and the crankshaft and camshaft sensors tell the engine computer where each cylinder is so it can inject fuel and, on gasoline engines, fire the spark.
The oil pump sends oil under pressure from the oil pan, through the filter, to the bearings, the camshafts, the lifters and the turbo. A sensor or switch watches the pressure and turns on the red light if it drops; many cars also measure the oil level and temperature and work out when it is due for a change.
The most common faults
- Low oil pressure: from a low level, a worn pump or filter or worn bearings; it can also be the sensor itself. Without pressure, the engine is damaged within minutes.
- Oil consumption: worn piston rings or valve seals, or a turbo letting oil through: bluish smoke and topping up between changes.
- Valve timing out of phase: a stretched chain, a belt that has jumped a tooth or a cam phaser that does not respond; the computer sees it as a crankshaft-camshaft mismatch.
- Crankshaft or camshaft sensors: when they fail, the engine may not start, may stall while driving or may jerk.
- Oil leaks: valve cover or oil pan gaskets and seals; oil dripping onto the exhaust smells burnt and can catch fire.
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
Oil warning light on: what it means and what to do
Stop as soon as it is safe
Blue smoke from the exhaust: the engine is burning oil
See a garage soon
Burning smell in the car: what it could be and what to do
Stop as soon as it is safe
Knocking or pinking from the engine: what it means and what to do
Stop as soon as it is safe
Engine cranks but will not start: causes and what to do
Check without hurry
Car using oil: when it is normal and what to do
See a garage soon
Service reminder or wrench light on the dashboard: what to do
Check without hurry
Puddle under the car: how to tell which fluid is leaking
Check without hurry
Lifter tick or ticking engine noise: what it could be
Check without hurry
The most relevant trouble codes
- P0520Engine oil pressure sensor/switch A, circuit: malfunction
- P0521Engine oil pressure sensor/switch A: range/performance
- P0522Engine oil pressure sensor/switch A: signal low
- P0524Engine oil pressure: too low
- P0298Engine oil: over temperature
- P0011A camshaft position: timing over-advanced or system performance (bank 1)
- P0014B camshaft position: timing over-advanced or system performance (bank 1)
- P0016Correlation fault between crankshaft position and camshaft position (bank 1, sensor A)
- P0010A camshaft position actuator A (bank 1), control circuit open
- P0335Crankshaft position sensor A, circuit: malfunction
- P0340Camshaft position sensor A (bank 1 or single sensor), circuit: malfunction
- P3400Cylinder deactivation system (bank 1): malfunction
- P0219Engine: overspeed
Generic OBD-II/EOBD codes; each manufacturer adds its own. The same symptom can come from another system.
Code blocks of this system
- P34xxcylinder deactivation and camshaft actuators
- P00xxfuel and air metering and auxiliary emission controls
- P03xxignition system or misfire
- P26xxoutput signals, intake heater and fuel pump
- P05xxvehicle speed, idle control and auxiliary inputs
- P02xxfuel and air metering (injector circuit)
- P20xxparticulate filter, AdBlue and NOx
- P25xxturbo control
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
What should I do if the oil light comes on?
If it is the red one (pressure), stop the car as soon as it is safe and turn off the engine; check the level with the engine cold and do not drive on if the light stays on after starting. If it is amber (level or maintenance), top up with the oil in the manual and keep an eye on it.
How often should the oil be changed?
The manufacturer sets it for each engine: usually from 6,000 to 20,000 miles or once a year, and sooner with short trips or towing. In many cars the maintenance reminder works it out.
Can an OBD reader see the oil pressure?
It sees the codes of the pressure circuit (P0520 to P0524) and, on many cars, the live oil temperature. The actual pressure is not always published over OBD: sometimes only the manufacturer's tool sees it.