Contaminated or failed mass air flow sensor on bank 2; Intake air leak between the MAF sensor and throttle body (e.g., cracked intake boot, loose clamp); Damaged or corroded wiring or connector at the MAF sensor; Faulty engine control module (ECM) or software issue (less common); Clogged air filter or restricted intake path causing low airflow; Excessive oil or dirt buildup on the MAF sensing element from aftermarket air filters

DTC codes / BMW codes / P1117

P1117 · BMWMass Or Volume Air Flow Circuit Low Input Bank 2

Q: What does code P1117 mean?

Mass Or Volume Air Flow Circuit Low Input Bank 2. P1117 on a BMW indicates that the engine control module (ECM) has detected a low input signal from the mass air flow (MAF) sensor on bank 2, meaning the sensor's output voltage is below the expected range for the current engine operating conditions. This typically points to a faulty MAF sensor, a wiring issue, or an air leak between the sensor and the throttle body that causes unmetered air to enter the engine.

P1117 on a BMW indicates that the engine control module (ECM) has detected a low input signal from the mass air flow (MAF) sensor on bank 2, meaning the sensor's output voltage is below the expected range for the current engine operating conditions. This typically points to a faulty MAF sensor, a wiring issue, or an air leak between the sensor and the throttle body that causes unmetered air to enter the engine.

SystemPowertrain

Code typeBMW specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Rough idle or stumbling, especially when the engine is cold
Hesitation or flat spot during acceleration
Reduced engine power and poor throttle response
Increased fuel consumption due to incorrect air/fuel mixture
Occasional engine misfire or surging at steady speeds

Common causes, most likely first

Contaminated or failed mass air flow sensor on bank 2
Intake air leak between the MAF sensor and throttle body (e.g., cracked intake boot, loose clamp)
Damaged or corroded wiring or connector at the MAF sensor
Faulty engine control module (ECM) or software issue (less common)
Clogged air filter or restricted intake path causing low airflow
Excessive oil or dirt buildup on the MAF sensing element from aftermarket air filters

How to diagnose and fix it

Inspect the air intake system for leaks, cracks, or loose connections between the MAF sensor and throttle body
Check the MAF sensor connector and wiring for corrosion, damage, or loose pins
Clean the MAF sensor element with a dedicated MAF cleaner and re-test
Verify air filter condition and replace if clogged
Use a scan tool to monitor MAF sensor voltage and compare to BMW specifications
Perform a smoke test to detect unmetered air leaks
Replace the MAF sensor if cleaning and wiring checks do not resolve the low input signal

Before you replace the bank 2 MAF sensor

A low input code on a BMW MAF sensor is frequently caused by a torn intake boot or a loose clamp that lets unmetered air into the engine, so always smoke-test the intake before condemning the sensor.
Oil from an over-oiled aftermarket air filter can coat the MAF hot wire and skew the signal low, so cleaning the element often restores normal operation without parts replacement.
On some BMW engines, a failing bank 2 MAF sensor can be intermittent and only set the code under specific load or temperature conditions, so road-test with live data to catch the glitch.
The ECM may set P1117 even when the MAF sensor is functioning correctly if the signal wire has high resistance due to corrosion, so always check voltage drop on the signal circuit.
A low MAF input can also be caused by a restricted air filter or a collapsed intake hose that limits airflow, so inspect the entire intake tract before assuming the sensor is faulty.

Can I keep driving with P1117?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy acceleration or sustained high speeds because the incorrect air/fuel mixture can cause misfires and damage the catalytic converter over time. If the engine runs very rough or stalls, stop driving and have the vehicle towed.

Tools that help

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Guidance is general and written for BMW vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.