Engine light stays on steady

Code p0102, according to:

P0102 Cadillac Mass or Volume Air Flow Circuit Low Input

is "Mass or Volume air Flow Circuit Low Input"
Means that the computer isn't getting enough signal from your MAF sensor.

Check the link above for more information. MAF replacement isn't difficult.

P0102 Chevrolet - Mass or Volume Air Flow Circuit Low Input

Read more: http://engine-codes.com/p0102_chevrolet.html#ixzz38p5k1ZD8

Possible causes - Faulty mass air flow sensor
- Intake air leaks
- Dirty mass air flow sensor
- Dirty mass air filter
- Mass air flow sensor harness is open or shorted
- Mass air flow sensor circuit poor electrical connection

Before replacing the mass air flow sensor, try replacing the air filter and cleaning the air flow sensor with low compress air or mass air flow sensor cleaner. Reset code and drive vehicle. If the code comes back, it may be necessary to replaced the mass air flow sensor.


Read more: http://engine-codes.com/p0102_chevrolet.html#ixzz38p5tpWZk

P0121 is for TPS sensor, clean your throttle body. Use a rag, toothbrush and carb cleaner. Get it clean. P0102 is for Mass air flow sensor. Try cleaning it first. No toothbrush use qtips on tiny wires. Be careful not to break wires. It's located between air filter and throttle body. Clear light and retest. If 102 returns , replace mass air flow sensor. Also test all wires at sensors. Wiggle and pull. Resolder as needed

The O2 sensor (2 on V engines) are in the exhaust system pipes before the catalytic converter, the next sensor is the efficiency monitor for the catalytic converter system it looks like a O2 sensor but performs a much different function as far as testing goes. The codes you have follow.

P0420 - Catalyst System Efficiency Below Threshold Bank 1
What does this mean? In most cases it means the catalytic converter is worn out and that is sensed by the catalyst monitor I spoke of earlier.

P0102 - Mass or Volume Air Flow Circuit Low Input
Faulty mass air flow sensor
- Dirty mass air flow sensor (located in the air intake hose to the engine from the air cleaner)
- Dirty air filter
- Mass air flow sensor harness is open or shorted
- Mass air flow sensor electrical circuit poor connection
- Intake air leaks

P0102 - Mass Air Flow Sensor Circuit Malfunction

The mass air flow or MAF sensor is placed in the intake air duct between the air filter and the engine intake manifold. The MAF sensor measures the amount of intake air flow. The MAF sensor converts the air flow measurement into a voltage or frequency signal, with the voltage or frequency changing proportionally to the amount of air flow. The air flow sensor signal is monitored by the engine computer (ECM). The engine computer (ECM) uses the mass air flow signal to know the engine load and to calculate the proper amount of fuel injected. If the signal from the mass air flow sensor is out of expected range, the ECM detects a fault and sets the code P0100. For example, the mass air flow sensor signal could be higher than expected when the engine is not running or lower than expected with the engine running. A car with the code P0100 may have some driveability issues, such as stalling, lack of power, surging, hesitation, etc. In some cars, the code P0100 can cause the fail-safe mode where the engine speed would be limited to 2,500 - 3,000 rpm.
If there are other trouble codes present, they might need to be looked at first. Checking the freeze frame may help, as it may contain some important information. The freeze frame is a snapshot of the engine parameters at the moment when the fault was detected. The freeze-frame may show whether the vehicle was running or stopped, whether the air-fuel ratio was lean or rich, was the engine was cold or warmed up at the time of the malfunction. Read more about the freeze frame.

Read more about mass air flow sensor.

What could cause the code P0100:
- faulty or contaminated mass air flow sensor
- open or short in the mass air flow sensor electrical circuit
- open or short in the sensor power or ground circuit

- other electrical problem with the MAF sensor wiring, (corroded wires, bent terminals, bad ground connection, burned fuse, etc.
- vacuum leaks
- restricted air flow at or before the air filter
- wrong air flow sensor installed
- problem with ECM

P0102 - Mass Air Flow Sensor Circuit Low

The mass air flow or MAF sensor measures the amount of air entering the engine. The engine computer (ECM) uses the mass air flow signal to calculate the amount of fuel injected (read more how the MAF sensor works below). The code P0102 is set when the signal from the mass air flow sensor is lower than expected. Often a car may exhibit some driveability symptoms, such as lack of power, surging, hesitation on acceleration, hard starting, pinging (detonation), or rough idle when started cold. Often the codes P0171 or P0174 could also be stored along with the code P0102, as the incorrect air flow signal can cause the engine to run lean. The codes P0171 and P0174 indicate a lean condition. Checking the freeze frame might help in the diagnostic process. The freeze frame is stored in the ECM along with the trouble code. The freeze frame contains some recorded parameters (e.g. vehicle speed, engine temperature, fuel trim) at the moment when the fault was detected. The freeze frame can also be accessed with a scan tool.

What could cause the code P0102
- faulty or contaminated mass airflow sensor
- debris blocking the air flow at the mass air flow sensor
- unmetered air leaking past the MAF sensor (vacuum leaks)
- PCV system vacuum leaks
- restricted or collapsed intake air duct
- dirty or restricted air filter
- restricted air screen before the air filter
- improper application of aftermarket components (e.g. cold intake, modified air filter, etc.)
- wrong air flow sensor installed
- electrical problem with the MAF sensor wiring, connector, power supply or ground.
- problem with ECM
- in some cases other issues with the fuel injection system like a clogged catalytic converter or a faulty manifold absolute pressure sensor (MAP) can also cause the code P0102.

Solution for MAF repair

It is not an ECM/PCM problem.
P0102 - Mass or Volume Air Flow Circuit Low Input
Possible causes- Faulty mass air flow sensor
- Dirty mass air flow sensor
- Dirty air filter
- Mass air flow sensor harness is open or shorted
- Mass air flow sensor electrical circuit poor connection
- Intake air leaks Tech notes Before replacing the mass air flow sensor, try replacing the air filter and cleaning the air flow sensor with low compress air or mass air flow sensor cleaner. Reset code and drive vehicle. If the code comes back, it may be necessary to replaced the mass air flow sensor

The light will go on and off until the actual system has failed.

P0102 - Mass or Volume Air Flow Circuit Low Input.

Symptoms:
- Engine stall
- Engine running rough
- Excessive fuel consumption
- Excessive smoke
- Engine light ON

Possible Causes:
- Harness or connectors (The sensor circuit is open or shorted.)
- Intake air leaks
- Mass air flow sensor may be faulty

Possible Solutions:
- Replace air filter
- Clean air flow meter
- Replace air flow meter

P0102 is the generic DTC (Data Trouble Code) for (Mass or Volume Air Flow Circuit Low Input), and it would most likely be a fault with the MAF (Mass Air Flow) sensor.

The MAF sensor could be dirty or faulty, and there might even be restricted air flow to the MAF sensor (like a plugged up air filter). Also be sure that there are no air or vacuum leaks in the air induction system especially between the MAF sensor and the throttle body and that the hose clamps on the air induction system are all tight.

this vehicle most likely has a mass air flow sensor it may have got accidently unplugged or the air tube from mass airflow to engine is not connected well or it could be that you have indeed a bad mass air flow sensor they do make a special cleaner that you may want to try before purchasing a mass air flow sensor or purchasing one from salvage yard the symptoms you describe would be created by a bad massair flowsensor

poor start, very poor gas millage