P0104 OBD-II Trouble Code: Mass Airflow (MAF) Electrical Circuit Erratic and Irregular Output

Our certified mechanics come to you · Get a fair and transparent estimate upfront

Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0104 code

P0104 is a diagnostic trouble code (DTC) for "Mass Airflow (MAF) Electrical Circuit Erratic and Irregular Output". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$20.00
Toyota$20.00
BMW$20.00
SCHEDULE P0104 DIAGNOSTIC Get a fair and transparent estimate upfront

P0104 Trouble code definition

Mass Airflow (MAF) Electrical Circuit Erratic and Irregular Output

  • The Code P0104 code is often associated with a P0100, P0101, P0102 and P0103 codes.

What the P0104 code means

P0104 is the code for issues with the Mass Airflow (MAF) Sensor having inconsistent, erratic or irregular high output voltage/signal to the Engine Control Unit (ECU).

What causes the P0104 code?

The MAF Sensor having erratically high voltage output problems may have several causes:

  • The source of the problem is the sensor voltage is not sending correct voltage output required by the ECU.

  • The most basic problem is too inconsistent high air flow from the air cleaner the MAF sensor.

  • The wiring or MAF sensor may be bad or have a bad electrical connection. It also could be too close to higher voltage consumption components, especially alternators, ignition wires, etc. which would give incorrect signal interference.

  • The air intake system may have a large leak like a bad vacuum hose, air intake hose loose, loose hose clamps or other intake leak before the MAF sensor. The leaks can be cracks that open and close depending on engine speed and loading.

  • MAF sensors must operate within specific ranges to send correct signals for the ECU to adjust correctly for proper engine operation that are compatible with other sensor outputs.

What are the symptoms of the P0104 code?

  • P0104 code will be generally preceded by the Check Engine Light coming on the dashboard display.

  • Normally, the vehicle runs well enough to drive but does require attention.The engine runs close to normal but it may run slightly erratically, have less power, back fire and idle inconsistently higher than normal. Continued driving of the vehicle can cause internal engine damage.

How does a mechanic diagnose the P0104 code?

  • P0104 is diagnosed with an OBD- II scanner. A qualified technician should then reset the OBD- II fault codes and road test the vehicle to see if the code and engine warning light return. He can observe this by watching live data on his scanner while driving. If the code comes back, then the mechanic will need to do a careful inspection to determine if any electrical connector, wiring, sensor, air cleaner, intake and vacuum hoses, loose hose clamps and MAF issues.

  • If no problems are noted, then the next step is to have the technician do a circuit test with a multimeter that has a display to show sampling rate and sensor range voltage readings to determine if the MAF sensor output is really erratically high.

Common mistakes when diagnosing the P0104 code

Diagnostic errors are largely by not following the correct procedure. First, follow the test procedure for the connector, wiring and sensor.

  • Do not buy a MAF sensor unless the other tests indicate no problem and is determined to be bad.

  • Before buying a MAF sensor, try cleaning it with a specialized spray cleaner, like CRC 05110, made for MAF sensors as these often get considerable carbon build up from the emission system, especially at idle.

  • The air intake system may have simple causes like loose clamps, air hoses or vacuum lines, so a close inspection is necessary before buying an expensive MAF unit.

How serious is the P0104 code?

  • The P0104 code will not prevent the car from driving unless the leak is very large.

  • The MAF sensor problem can cause excessive fuel consumption, rough operation and difficulty starting in certain circumstances, or even engine damage if the vehicle is continued to be driven, but it is best to diagnose the problem more accurately.

  • Occasionally, the code can be reset and the vehicle will function normally without the engine warning light or the code returning.

  • Often times, if the engine warning light came on immediately at start up, and the OBD- II system can be reset and the vehicle will operate normally.

What repairs can fix the P0104 code?

The most common repairs to address the P0104 code are as follows:

  • Verify the code with a scanner. Reset the fault codes with the OBD-II Scanner and perform a road test.

  • If the P0104 code and/or engine warning light comes back, then follow the test procedure.

  • Inspect the electrical connector to insure it is attached. Disconnect it and then reinstall to make sure there is a fresh electrical connection.

  • Closely inspect for wiring being frayed or broken on the connector. Repair or replace as necessary before proceeding.

  • Check the air intake system for vacuum leaks, loose hoses and clamps on the intake, especially on older cars.

  • Replace the MAF sensor if no other issues are found.

Additional comments for consideration regarding the P0104 code

Many vehicles with mileage over 100,000 have momentary sensor problems that usually occur during start up or prolonged stress situations on the drive train.

If the engine warning light comes on and the vehicle seems to be operating normally, the OBD-II system can be reset using the scanner and the problem may not reoccur. This is why it is important to verify the fault and reset it before doing any repairs.

Need help with a P0104 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

P0104
trouble codes
Check Engine Light

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P0104 code.

SCHEDULE P0104 DIAGNOSTIC
Get a $20 credit for the follow-up repair

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.8/5

Number of Reviews

5,170

Rating Summary
4,765
197
50
27
131
4,765
197
50
27
131

Fred

16 years of experience
364 reviews
Fred
16 years of experience
Mercedes-Benz E500 - Check Engine Light is on - Conroe, Texas
Fred was very friendly and thorough to get to the root of the issue. Even when he could not find a fault to why my engine light was on, he went above and beyond to make absolutely sure that the concern was minimized. Turns out, all that needed to be done was a reset but his diagnostic to address my issues was very intricate and appreciated.

David

17 years of experience
37 reviews
David
17 years of experience
Chevrolet Cruze - Check Engine Light is on - Aurora, Colorado
David was on time, professionalisms & honest! I would definitely request him again and pass along to friends/family.

John

18 years of experience
18 reviews
John
18 years of experience
Dodge Ram 1500 - Check Engine Light is on - Memphis, Tennessee
Demonstrated good integrity. Advised me when work I thought needed done was unnecessary and was helpful in identifying issues that needed to be addressed

Robert

21 years of experience
17 reviews
Robert
21 years of experience
Chrysler 200 - Check Engine Light is on - Fort Worth, Texas
Robert did a good job working on my car and letting me know what's needed to keep my car driving smoothly.


Related questions

Nothing happens when I push the gas pedal

The P0104 is probably the key. This is a code for the Mass Air Flow circuit. What it means is that the reading from the MAF is not along the lines of what the ECU expects. The 171 and 174...

Truck won't run like it used to

Hi, thanks for writing in. Believe it or not, this happens quite a bit when people swap OEM air filters to K&N or other products. It has nothing to do with the aftermarket part however. The P-0104 OBD-II error code...

More related articles

P2634 OBD-II Trouble Code: Fuel Pump B Control Circuit High
P2634 means that there is an issue with the fuel pump B control due to the circulation being high, defective fuel pump or fuel relay, or broken wire.
P0067 OBD-II Trouble Code: Air Assisted Injector Control Circuit High
P0067 P0067 trouble code definition Air Assisted Injector Control Circuit High What the P0067 code means The P0067 code means that the powertrain control module (PCM) is detecting a higher voltage from the air assisted injector system circuit than was...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com