92 Es300 Non Obd Code 25

[flippu10]

Hello everyone,

My CEL went on and I pulled a non OBD code of 25. According to the description of possible causes, Manifold Air Temperature (MAT) sensor is reporting abnormally high readings - defective MAT. Is the MAT the same as Mass Airflow Sensor. If not can someone point me to where I can find it. Thanks.

[Toysrme]

Code 25 means that you're running lean.

Reset the ECU (Pull the EFI fuse for a second & put it back in) See if it reoccures. Either way I say check:

vacuum leaks

output & responce of both o2 sensors

Coolant temp sensor

AFM output (VS)

IAT output

Fuel pressure

In that order.

FYI You don't have a MAT, you have an IAT. (Intake Air Temperature) it's a little thing hanging at the front of the AFM housing measuring intake temp.

That being said, I doubt it's the IAT. Most likely a vacuum leak, or o2 sensors.

If you've got over 100,000 miles on the current 2 o2 sensors, ditch them. Generic splice in Bosch replacements only cost $30-35.

[flippu10]

Thanks, Toys. I'll check it out. The 2 O2 sensors are fairly new, definitely less than 50K miles. I'll reset the ECU and then do the check as you suggested.

In resetting the ECU, do you take the fuse out and hold while the car is running?

Code 25 means that you're running lean.

Reset the ECU (Pull the EFI fuse for a second & put it back in) See if it reoccures. Either way I say check:

vacuum leaks

output & responce of both o2 sensors

Coolant temp sensor

AFM output (VS)

IAT output

Fuel pressure

In that order.

FYI You don't have a MAT, you have an IAT. (Intake Air Temperature) it's a little thing hanging at the front of the AFM housing measuring intake temp.

That being said, I doubt it's the IAT. Most likely a vacuum leak, or o2 sensors.

If you've got over 100,000 miles on the current 2 o2 sensors, ditch them. Generic splice in Bosch replacements only cost $30-35.

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[flippu10]

I forgot to ask, what's an AFM, for future reference.

Thanks, Toys.  I'll check it out.  The 2 O2 sensors are fairly new, definitely less than 50K miles.  I'll reset the ECU and then do the check as you suggested.

In resetting the ECU, do you take the fuse out and hold while the car is running?

Code 25 means that you're running lean.

Reset the ECU (Pull the EFI fuse for a second & put it back in) See if it reoccures. Either way I say check:

vacuum leaks

output & responce of both o2 sensors

Coolant temp sensor

AFM output (VS)

IAT output

Fuel pressure

In that order.

FYI You don't have a MAT, you have an IAT. (Intake Air Temperature) it's a little thing hanging at the front of the AFM housing measuring intake temp.

That being said, I doubt it's the IAT. Most likely a vacuum leak, or o2 sensors.

If you've got over 100,000 miles on the current 2 o2 sensors, ditch them. Generic splice in Bosch replacements only cost $30-35.

←

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[Toysrme]

Air-Flow Meter

M!Removed! Air-Flow

Manifold Air Pressure

Karman Vortex

We've got an AFM.

All are ways of derriving how much airflow is entering the engine - so the ECU knows roughly how much fuel to squirt.

No if you pull the fuse out you cut power to the ECU. At which point you no longer have fuel, or spark.

Just pull the fuse out & put it back. Don't play with wires or a running car.