What Does P1104 Mean?
P1104 signals an intermittent malfunction in the Mass Air Flow (MAF) sensor circuit, or that the OBD-II readiness monitors have not completed their self-test cycles. This dual-meaning code commonly appears after a battery disconnect or ECM reset. If the MAF is the root cause, you may notice erratic idle, hesitation, or poor fuel economy from incorrect airflow measurement.
Common Causes
30%
Dirty or contaminated MAF sensor element
25%
Intermittent wiring connection at the MAF sensor connector
20%
OBD-II monitors incomplete after recent battery or ECM reset
15%
Air leak in the intake tract between MAF sensor and throttle body
10%
Failing MAF sensor with intermittent internal fault
Diagnostic Steps
1
Step 1: Check OBD-II readiness monitor status. If monitors show incomplete, perform a drive cycle to allow all monitors to run before further diagnosis.
2
Step 2: Monitor MAF sensor data (grams/second) at idle and under load. At idle, expect 2–7 g/s for most 4-cylinder engines and 5–15 g/s for V6/V8. Erratic or frozen readings indicate a sensor fault.
3
Step 3: Visually inspect the MAF sensor connector for corrosion, bent pins, or loose fit. Wiggle the connector while monitoring live data for signal dropouts.
4
Step 4: Clean the MAF sensor element with dedicated MAF cleaner spray. Do not touch the hot wire/film element. Allow to fully dry before reinstalling.
5
Step 5: Inspect the air intake duct from the air filter to the throttle body for cracks, loose clamps, or disconnected hoses that could allow unmetered air.
6
Step 6: If cleaning and wiring checks do not resolve the intermittent fault, replace the MAF sensor. Clear codes and complete a full drive cycle.
Estimated Repair Cost
$30 - $300
Parts + labor, varies by vehicle and location
P1104 signals an intermittent malfunction in the Mass Air Flow (MAF) sensor circuit, or that the OBD-II readiness monitors have not completed their self-test cycles. This dual-meaning code commonly appears after a battery disconnect or ECM reset. If the MAF is the root cause, you may notice erratic ...
The most common cause of P1104 (MAF Sensor Intermittent/ Check of all OBDII Systems Not Complete) is: Dirty or contaminated MAF sensor element
Typical repair costs for P1104 range from $30 to $300, depending on the vehicle, location, and whether you do it yourself or go to a shop.
An intermittent MAF fault can cause sudden hesitation or surging, which may be hazardous during acceleration in traffic. The vehicle remains generally safe to drive but should be diagnosed promptly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1104 to identify the root cause.
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Quick Info
Category
Powertrain
System
Engine Management / Air Metering
Difficulty
Type
Manufacturer
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