What Does P1140 Mean?
This code indicates the mass air flow (MAF) sensor or volume air flow (VAF) sensor output is outside the expected range for the current engine operating conditions, or the sensor is not responding proportionally to changes in engine load and speed. The ECM uses this sensor as the primary input for fuel injection calculations, so a range or performance issue directly impacts fuel metering accuracy and drivability.
Common Causes
30%
Contaminated MAF sensor hot wire or hot film element
25%
Air leak in the intake tract between the MAF sensor and throttle body
15%
Dirty or restricted air filter reducing airflow accuracy
15%
Damaged or deteriorated MAF sensor element
15%
Incorrect MAF sensor installed or intake tube not properly sealed
Diagnostic Steps
1
Monitor MAF sensor grams per second reading at idle (typically 2-7 g/s) and at 2500 RPM (typically 15-25 g/s depending on engine size); compare to known-good values.
2
Inspect the intake air duct between the MAF sensor and throttle body for cracks, loose clamps, or disconnected hoses that allow unmetered air.
3
Check and replace the air filter if it is excessively dirty or has been installed incorrectly.
4
Carefully clean the MAF sensor element with dedicated MAF cleaner spray; do not touch the sensing element.
5
Verify the MAF sensor voltage or frequency output scales proportionally with RPM increase using a scan tool graph.
6
Replace the MAF sensor if cleaning does not restore proper readings.
Estimated Repair Cost
$30 - $350
Parts + labor, varies by vehicle and location
This code indicates the mass air flow (MAF) sensor or volume air flow (VAF) sensor output is outside the expected range for the current engine operating conditions, or the sensor is not responding proportionally to changes in engine load and speed. The ECM uses this sensor as the primary input for f...
The most common cause of P1140 (Mass or Volume Air Flow Circuit Range/Performance Problem) is: Contaminated MAF sensor hot wire or hot film element
Typical repair costs for P1140 range from $30 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A faulty MAF sensor can cause hesitation, stalling, or surging during acceleration. While not a direct safety hazard, sudden loss of power at highway speeds or while merging could create a dangerous driving situation.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1140 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel System / Air Induction
Difficulty
Type
Manufacturer
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