Leaking or burnt exhaust or inlet valve on cylinder 8, or a valve not seating properly; Worn or broken piston rings or scored cylinder bore on cylinder 8; Head gasket failure leaking compression from cylinder 8 to an adjacent cylinder, coolant or the outside; Valve timing fault, such as a stretched or jumped timing chain or belt, or a faulty variable valve timing system; Underlying misfire from an ignition or injector fault on cylinder 8 distorting the pressure reading; Faulty in-cylinder pressure sensor, wiring or connector, where the engine is fitted with one; Damaged piston, cracked cylinder head or bent valve after overheating or a timing failure.

P03E0

Cylinder 8 Pressure Too Low.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
3: AreaIgnition system or misfire
E0: FaultThe specific fault in that area

What it means

P03E0 is the generic code for Cylinder 8 Pressure Too Low. The engine control unit has judged that the pressure developed in cylinder 8 is below the expected level. Depending on the vehicle, this comes from an in-cylinder pressure sensor or is inferred from crankshaft speed behaviour. The exact detection method and thresholds depend on the make, model and engine, so check the manufacturer data for the vehicle.

Symptoms

Engine management warning light on
Rough running or a noticeable shake at idle
Loss of power, especially under load
Misfire on cylinder 8, possibly with a flashing warning light
Increased fuel consumption or rough cold starts
Raw fuel or exhaust smell from the tailpipe

Possible causes

Leaking or burnt exhaust or inlet valve on cylinder 8, or a valve not seating properlylikely
Worn or broken piston rings or scored cylinder bore on cylinder 8likely
Head gasket failure leaking compression from cylinder 8 to an adjacent cylinder, coolant or the outsidepossible
Valve timing fault, such as a stretched or jumped timing chain or belt, or a faulty variable valve timing systempossible
Underlying misfire from an ignition or injector fault on cylinder 8 distorting the pressure readingpossible
Faulty in-cylinder pressure sensor, wiring or connector, where the engine is fitted with onerare
Damaged piston, cracked cylinder head or bent valve after overheating or a timing failurerare

How to diagnose

Read all stored and pending codes and the freeze frame data, noting engine load, speed and temperature when the code set, and look for misfire codes on cylinder 8 (P0308) or other cylinders.
Check for service bulletins and known engine faults for the specific model and engine.
Inspect the wiring and connectors for cylinder 8 ignition, injector and any pressure sensor for damage, corrosion or poor contact.
Swap or test the ignition coil, spark plug and injector on cylinder 8 to rule out a misfire source, and check fuel and ignition condition.
Check engine oil and coolant levels and condition for signs of coolant loss, oil contamination or fuel dilution.
Check the valve timing against the manufacturer's procedure, including any variable valve timing data from live readings.
Carry out a compression test on all cylinders and compare cylinder 8 with the others and with the manufacturer's specification.
If compression is low, carry out a cylinder leak-down test and a borescope inspection to find whether the leak is at the valves, rings or head gasket.

How to fix

Repair or replace the leaking valves and recondition the cylinder head as needed.
Repair worn piston rings or bore damage with an engine overhaul or replace the engine, as the condition requires.
Replace the head gasket and check the head and block for flatness and cracks.
Correct the valve timing, replacing the chain, belt, tensioners or variable timing parts that are worn or faulty.
Replace the faulty ignition, injector or in-cylinder pressure sensor, and repair damaged wiring or connectors.

Can I keep driving?

Medium severity

Limit driving and get it checked soon, as low pressure on a cylinder can cause misfires that may damage the catalytic converter and the engine. If the warning light flashes, there is a severe misfire, or you notice coolant loss or overheating, stop driving and have the car recovered.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.