Audi A4 B7 and B8: oil consumption, chain, and carbon — three topics to check together

The A4 of these generations has three main topics, and they are causally connected. So check them together: find one and go looking for the other two.

1. Oil consumption

The best-known topic on turbocharged petrol engines of this period. On some engines oil consumption is noticeably higher than expected.

What diagnostics shows: directly, nothing — there is no “oil burned” parameter. Indirectly:

• Oily deposits on the spark plugs.
• Misfires P0300–P0304.
• P0420 — the catalyst suffers from oil in the exhaust.

What an owner should do: check the dipstick every 600 miles. Here that is not caution but operational necessity.

2. Carbon on the intake valves

A direct consequence of the first topic plus direct injection.

Fuel goes straight into the cylinder and never washes the valves. Oil vapour from the crankcase ventilation settles and bakes on. The more oil the engine consumes, the faster the carbon grows.

Signs at 60,000–90,000 miles: rough idle, lost low-end torque, misfires, rising fuel consumption.

What shows: misfire counters and unstable fuel trims at idle. Full coverage in the GDI carbon buildup guide.

3. Timing chain and tensioner

The third topic, and the most expensive.

Signs:

• A rattle on cold start — 1–3 seconds, growing longer over time.
• Code P0016.
• Alongside it P0011 or P0014.

The link to the previous topics: oil condition decides everything here. An engine consuming oil and serviced rarely wears its chain faster. Covered in the P0016 guide.

A cold start at inspection is mandatory. It is the only way to hear the chain, and sellers know it.

What else to check

Crankcase ventilation valve. When it fails it produces several effects at once: a vacuum leak (P0171), increased oil consumption, unstable idle. A cheap part with outsized influence.

Purge valve. EVAP codes: P0442, P0455. Before replacing it, tighten the fuel cap until it clicks.

Water pump and thermostat. On some engines they form one assembly with a plastic housing that cracks. Signs: P0128, coolant leaks, a cold heater.

Cam phasers. P0011, P0014 — but do not confuse them: if P0016 is present alongside, the chain is the problem, not the phasers. The distinction is in the cam phaser guide.

High-pressure fuel pump. On some direct-injection engines it is driven from a camshaft lobe, and the follower/lobe pair wears. Signs: P0087, hesitation under load, knocking.

Inspection order when buying

1. A cold start is mandatory — listen to the first seconds.
2. Oil level and condition on the dipstick — a direct indicator of everything else.
3. Read codes, pending and permanent included.
4. Look for P0016 — the main fork in ownership cost.
5. Per-cylinder misfire counters — they reveal carbon.
6. Fuel trims at idle — they reveal the crankcase ventilation valve.
7. Readiness monitors — all not ready means the memory was just cleared.
8. Ask the seller how much oil gets topped up between changes. On these engines “I never top it up” is worth verifying on the dipstick.

The full protocol is in the used car inspection guide.

In short

• The three main topics are linked: oil → carbon → chain. Check them together.
• Diagnostics cannot see oil consumption — dipstick only, every 600 miles.
• P0011 together with P0016 means the chain, not the phaser.
• The crankcase ventilation valve is a cheap part with three separate consequences.
• A cold start at inspection is the only way to hear the most expensive problem.

Download the app — codes, freeze frames, trims, and misfire counters are read with an ELM327 adapter over Bluetooth SPP on Android.