P0104
Fix within a few daysThe Mass Air Flow (MAF) sensor is sending an inconsistent or erratic signal to your engine's computer.
Code P0104 means your Mass Air Flow (MAF) sensor signal is intermittent. Common causes: Dirty/faulty MAF sensor (60%), wiring issues (20%), vacuum leaks (10%). Drivability: Yes, for short trips, but fix soon. Repair cost: $10-$200 DIY, $150-$400 professional.
Can I Drive With P0104?
Yes, for short trips only
Essential trips under 10 miles, avoid highways and heavy acceleration
Stop driving immediately if: Flashing Check Engine Light, significant power loss, engine stalling frequently, black smoke from exhaust
Symptoms of P0104
- 1Check Engine Light is on
- 2Engine runs rough or idles poorly
- 3Engine stalls, especially at idle or when coming to a stop
- 4Poor acceleration or hesitation
- 5Reduced fuel economy
- 6Engine may be hard to start
Common Causes of P0104
Parts most likely causing this code, ranked by probability
A dirty or faulty MAF sensor cannot accurately measure incoming air, leading to erratic signals.
60% of P0104 cases are fixed by replacing or cleaning the MAF sensor
Corroded, loose, or damaged wires and connectors can cause intermittent signal loss from the MAF sensor.
20% of P0104 cases are fixed by repairing MAF sensor wiring or connector
Unmetered air entering the engine through a vacuum leak can cause the MAF sensor's readings to appear erratic to the engine computer.
10% of P0104 cases are fixed by repairing vacuum leaks
A severely clogged air filter restricts airflow, which can cause the MAF sensor to report inconsistent or incorrect air mass readings.
5% of P0104 cases are fixed by replacing a dirty air filter
A rare but possible cause is a faulty engine computer that cannot correctly process the MAF sensor's signal.
5% of P0104 cases are fixed by replacing or reprogramming the ECM
Check These First (Before Buying Parts)
- Inspect your air filter for dirt or obstructions and replace if needed.
- Visually check the MAF sensor's electrical connector and wiring for any signs of damage, corrosion, or loose connections.
- Carefully remove and clean the MAF sensor with a specialized MAF sensor cleaner.
How to Diagnose P0104
- 1Inspect the air filter for dirt or obstructions and replace if necessary.
- 2Visually check the MAF sensor wiring harness and connector for damage, corrosion, or loose connections.
- 3Carefully remove the MAF sensor and clean it with a dedicated MAF sensor cleaner.
- 4Check for vacuum leaks around the intake manifold, vacuum lines, and PCV system using a smoke machine or by listening for hissing sounds.
- 5Use a scan tool to monitor MAF sensor readings (grams/second) at idle and during acceleration to identify erratic behavior.
- 6If all other checks are inconclusive, test the MAF sensor's voltage output with a multimeter according to service manual specifications.
P0104 on Popular Vehicles
Ford F-150
2004-2024Ford F-150s are prone to MAF sensor issues, particularly if the air filter is neglected or if aftermarket oiled air filters are used, which can contaminate the sensor. Always check for intake leaks around the throttle body and airbox.
70% fixed by cleaning or replacing MAF sensor and/or air filter
Honda Accord
2003-2024Honda Accords can experience P0104 due to MAF sensor contamination or wiring issues. Pay close attention to the MAF sensor connector for corrosion or loose pins, as these are common failure points.
80% fixed by cleaning/replacing MAF sensor or repairing wiring
Toyota Camry
2007-2024Toyota Camry vehicles with P0104 often point to a dirty MAF sensor or a small vacuum leak. Inspect all vacuum lines carefully, especially those connected to the intake manifold, as they can become brittle over time.
75% fixed by cleaning/replacing MAF sensor or fixing vacuum leaks
Frequently Asked Questions
What does P0104 mean?
P0104 indicates that your vehicle's engine computer is receiving an intermittent or erratic signal from the Mass Air Flow (MAF) sensor. This means the computer isn't getting a consistent reading of how much air is entering the engine.
Can I drive with P0104?
Yes, for short trips only. You can drive your vehicle with a P0104 code, but you should limit driving and fix it within a few days. The engine might run rough, stall, or have reduced power, and prolonged driving with an incorrect fuel mixture can damage your catalytic converter.
Will P0104 clear itself?
No, P0104 will not clear itself. The engine computer stores this code when it detects an ongoing issue with the MAF sensor signal. You must diagnose and fix the underlying problem, then clear the code with a scan tool or by disconnecting the battery for a short period.
How do I fix P0104 myself?
Start by checking your air filter and replacing it if it's dirty. Next, inspect the MAF sensor wiring and connector for any damage. Then, remove and clean the MAF sensor with a specialized MAF sensor cleaner. If the code persists, you may need to replace the MAF sensor or check for vacuum leaks.
How much does it cost to fix P0104?
The cost to fix P0104 yourself ranges from $10 (for MAF cleaner) to $200 (for a new MAF sensor). If you take it to a professional shop, expect to pay between $150 and $400, which includes diagnosis and parts replacement.
P0104 keeps coming back - why?
If P0104 keeps returning, it often means the initial repair didn't address the root cause. Common reasons for recurrence include a faulty MAF sensor that was not replaced, persistent wiring issues, an undetected vacuum leak, or a rare problem with the engine computer itself.
Will P0104 fail emissions/smog test?
Yes, P0104 will cause your vehicle to fail an emissions or smog test. The Check Engine Light being on is an automatic failure in most jurisdictions, and the underlying issue with air metering directly impacts exhaust emissions.
What's the difference between P0104 and P0101?
P0104 indicates an intermittent or erratic MAF sensor signal, meaning the signal is inconsistent. P0101 indicates a MAF sensor performance problem, meaning the signal is consistently out of the expected range, but not necessarily intermittent.
P0104 on Ford F-150
On Ford F-150s, P0104 is commonly caused by a dirty or failing MAF sensor, especially on trucks with aftermarket air intake systems or those driven in dusty conditions. Always check the air filter and clean the MAF sensor first before considering replacement.
Questions to Ask Your Mechanic
Did you check the MAF sensor's live data readings with a scan tool at different RPMs?
Good answer: Yes, I monitored the grams per second (g/s) at idle and during a test drive. The readings were erratic and inconsistent with expected values for this engine.
Did you perform a smoke test to check for vacuum leaks?
Good answer: Yes, I performed a smoke test on the intake system and found no leaks. The system is sealed.
Repair Cost Estimate
DIY Repair
Parts only
$10-$200
Shop Repair
Parts + labor
$150-$400
Save $140-$200 by doing it yourself
Difficulty
intermediate
Time
0.5-1.5 hours
Intermediate - Cleaning the MAF sensor and checking wiring is beginner-friendly, but diagnosing vacuum leaks or using a scan tool effectively requires intermediate skills.
Cost of Waiting
Ignoring P0104 can lead to significantly reduced fuel economy, poor engine performance, and potentially damage your catalytic converter due to the engine running too rich or too lean. A $10 MAF cleaner or $150 sensor replacement now prevents a $1,200-$2,500 catalytic converter replacement later.
While You're In There...
Often removed to access the MAF sensor and a dirty filter can contribute to MAF issues. Replace it to ensure proper airflow.
If you're diagnosing vacuum leaks, the intake manifold gasket is a common source and replacing it prevents future leaks.
Tools You'll Need
- OBD-II Scan Tool
- MAF Sensor Cleaner
- Screwdriver set or Socket set
- Multimeter (for advanced diagnostics)
- Smoke machine (for vacuum leak detection)
P0104 is a common code related to your engine's air intake system. Most repairs are straightforward, often involving a simple cleaning or replacement of the MAF sensor, and your engine will run smoothly again.
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Your Next Steps
Step 1: Check your air filter and replace it if it's dirty. Then, inspect the MAF sensor wiring and connector for any visible damage or corrosion.
Step 2: If the wiring looks good, remove the MAF sensor and clean it thoroughly with MAF sensor cleaner. Reinstall and clear the code.
Step 3: If the code returns, use a scan tool to monitor MAF sensor readings. If they are still erratic or incorrect, replace the MAF sensor. Also, perform a thorough check for vacuum leaks.