Contaminated or failed bank 2 mass air flow sensor; Short to voltage in the MAF sensor signal circuit; Corroded or loose electrical connector at the bank 2 MAF sensor; Intake air leak downstream of the MAF sensor (unmetered air); Faulty engine control module (ECM) driver circuit (less common); Wiring harness damage from chafing or heat exposure

DTC codes / BMW codes / P1118

P1118 · BMWMass Or Volume Air Flow Circuit High Input Bank 2

Q: What does code P1118 mean?

Mass Or Volume Air Flow Circuit High Input Bank 2. P1118 on BMW vehicles indicates that the engine control module (ECM) has detected an abnormally high signal voltage from the bank 2 mass air flow (MAF) sensor circuit, which typically corresponds to a condition where the sensor is reporting more air entering the engine than is physically possible. The ECM sets this code when the MAF sensor signal exceeds the maximum expected threshold for a calibrated period, often due to a wiring short to voltage, a contaminated sensor element, or a faulty sensor.

P1118 on BMW vehicles indicates that the engine control module (ECM) has detected an abnormally high signal voltage from the bank 2 mass air flow (MAF) sensor circuit, which typically corresponds to a condition where the sensor is reporting more air entering the engine than is physically possible. The ECM sets this code when the MAF sensor signal exceeds the maximum expected threshold for a calibrated period, often due to a wiring short to voltage, a contaminated sensor element, or a faulty sensor.

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, particularly when the engine is cold
Hesitation or flat spots during acceleration
Poor fuel economy due to incorrect air mass reporting
Black smoke from the exhaust or a strong fuel odor indicating a rich running condition
In rare cases, the engine may enter limp mode with reduced power

Common causes, most likely first

Contaminated or failed bank 2 mass air flow sensor
Short to voltage in the MAF sensor signal circuit
Corroded or loose electrical connector at the bank 2 MAF sensor
Intake air leak downstream of the MAF sensor (unmetered air)
Faulty engine control module (ECM) driver circuit (less common)
Wiring harness damage from chafing or heat exposure

How to diagnose and fix it

Inspect the bank 2 MAF sensor connector and wiring for corrosion, looseness, or damage; clean or repair as needed
Check the MAF sensor signal circuit for a short to voltage using a digital multimeter (DMM) and wiring diagram
Clean the MAF sensor element with a dedicated MAF cleaner and re-test; replace if contamination is severe
Perform a smoke test to check for intake leaks between the MAF sensor and throttle body
Compare live bank 2 MAF sensor readings with bank 1 (if equipped) or with expected values using a scan tool
Replace the bank 2 MAF sensor if cleaning and wiring repairs do not resolve the high signal voltage
Clear the fault memory and verify the repair by test-driving the vehicle and monitoring MAF sensor data

Don't replace the MAF sensor before checking these

A high input code often results from a short to voltage in the signal wire, not a failed sensor; always check the harness for rubbed-through insulation near hot components.
Unmetered air from a cracked intake boot or leaking vacuum hose can cause the MAF sensor to report a higher air mass than actual, triggering P1118 on bank 2.
On BMW engines with two MAF sensors, swapping bank 1 and bank 2 sensors can help isolate whether the fault follows the sensor or stays with the circuit.
A dirty MAF sensor element from an oiled air filter or excessive oil mist can skew readings high; cleaning may resolve the code without replacement.
The ECM itself rarely fails, but a shorted driver circuit inside the ECM can mimic a sensor fault; confirm wiring integrity before condemning the module.

Can I keep driving with P1118?

You can drive the vehicle with P1118, but avoid aggressive acceleration and heavy loads until the fault is repaired, as incorrect air mass readings can cause rich running, poor fuel economy, and potential damage to spark plugs or the catalytic converter over time.

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.