P0174

System Too Lean (Bank 2)

Symptoms

• •Rough idle
• •Hesitation
• •Reduced economy

Likely causes

• •Vacuum/intake leak
• •Dirty MAF sensor
• •Weak fuel pump

Can I drive?

Diagnose soon.

Estimated repair cost (Malaysia)

RM200–RM800 (approximate)

Diagnostic guide (for mechanics)

Work through these in order — cheapest and safest checks first, before replacing expensive parts.

1. 1. Read fuel trims (bank 2)

   Confirm the lean condition and where it appears (idle vs load).

   Test: Live data short/long-term fuel trim bank 2.

   Expected: Lean = positive trims above +10%.

2. 2. Smoke-test for vacuum/intake leaks

   A leak is the most common bank-2 lean cause.

   Test: Smoke test the intake; inspect hoses and gaskets.

   Expected: No smoke escaping.

3. 3. Inspect MAF and fuel delivery

   A dirty MAF or weak fuel supply starves the mixture.

   Test: Live data MAF; fuel pressure under load.

   Expected: Plausible airflow; pressure holds.

Tools: OBD-II scan tool · Smoke machine · Fuel-pressure gauge

When to escalate: If both banks read lean, suspect a shared cause (MAF, fuel pressure, or a large vacuum leak).

This is general information, not a diagnosis. AutoMalaya OBD helps explain your car’s actual scan data; a qualified mechanic may still need to inspect the vehicle.

Related fault codes

See sample report