2013 Mercedes-Benz P0171: What It Means & Is It Safe to Drive?
P0171 on the 2013 Mercedes-Benz: System Too Lean (Bank 1). Here's what it means, what usually causes it, what repairs typically cost, and whether it's safe to keep driving.
What this code means
The engine is getting too much air relative to fuel. The O2 sensor sees excess oxygen in the exhaust and the PCM is adding more fuel than normal to compensate.
Common causes on the 2013 Mercedes-Benz
- Dirty or faulty mass airflow (MAF) sensor
- Vacuum leaks (PCV hose, intake gasket, brake booster)
- Weak fuel pump or clogged fuel filter
- Leaking or stuck open fuel injectors (less common)
Symptoms
- Check Engine Light
- Rough idle, hesitation, lack of power
- Possible spark knock under load
- Poor fuel economy
Typical fixes
- Clean or replace MAF sensor
- Locate and seal vacuum leaks
- Replace fuel filter / test fuel pressure
- Smoke test intake system
Repair cost range
For a 2013 Mercedes-Benz, repairs for P0171 typically fall between $50 and $500, depending on the root cause and labor rates in your area.
Known issues on Mercedes-Benz
Mercedes P0171 on M274 2.0T engines is frequently an SAI (Secondary Air Injection) pump failure—the SAI pump injects air into the exhaust manifold during cold starts to help catalytic converter light-off. When the SAI pump or check valve fails, the ECU sees a lean condition during startup and sets P0171. On M272/M276 V6 engines, the intake manifold secondary air passages clog with carbon deposits. On M271 1.8T Kompressor, the charge air hose from the supercharger to the throttle body splits under boost. Always perform a smoke test on M-B engines before replacing sensors.
Most commonly affected models