Nissan altima 2000 with engine service light on. fault codes per mechanic p0325 and p1126. But he said mass air flow sensor malfunction. is this right?

You will need to get a Good Mechanic to look at this. There are 3 completely different problems here so it will need to be properly checked out. I've listed the Trouble Code definitions below.
-The knock sensor looks for signs of the fuel igniting at the wrong point in the sequence.
-The Crankshaft position sensor checks the pistons are in the correct position for the engine electronics to be in the correct sequence.
-The Air Control system is a set of valves that adjust air flow through the engine when running at different speeds. (Slow needs less air, fast needs more air).
Knock Sensors and Crankshaft Position Sensors can be in some ridiculous places on an engine and usually need major surgery to get to them. Air control systems could be anything from a 'sticky' valve to a faulty sensor.

P0325 = Knock sensor (KS) 1, bank 1 - circuit malfunction
P0335 = Crankshaft position (CKP) sensor - circuit malfunction
P0505 = Idle Air Control System

Replace the coolant thermostat. The code is different on a Nissan and actually refers to a thermostat fault. Replace the thermostat and clear the codes, you're fixed

ok lets start with the codes they say your getting. P??? which 1's and how many. there are few o2 sensors, are they next to the Exhaust next to the converter? MASS AIR FLOW -MAF use this, for now i am guessing, until i see the correct codes your are getting. this could be the 1 you may have below, please read it........

• P0103
  Mass Air Flow Sensor Circuit High Input
• 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.
• possible symptoms Engine Light ON (or Service Engine Soon Warning Light)
  - Engine stall
  - Engine running rough
  - Excessive fuel consumption
  - Excessive smoke
• the code is generated when An excessively high voltage from the sensor is sent to Engine Control Module (ECM).

2003 NISSAN Altima Sedan OBDII Codes List

p0171 = fuel system too lean, this means vacuum leak or faulty oxygen sensor

p0303 = cylinder 3 misfire

p0325 = knock sensor malfunction.

p0303 and p0325 - i can see these working together, if a cylinder misfires, it will cause the knock sensor to trip. I would lean towards the coil and or ignition module, along with a faulty oxygen sensor.

Your battery has nothing to do with these codes. Your vehicles computers have detected a malfunction or failure in the system. This triggers these codes and sets your check engine light. Below I have listed the code meanings and some repair solutions.

P1126 - Throttle Position (Narrow Range) Sensor Circuit Malfunction.

Power supply for the throttle control motor is provided to the ECM via throttle control motor relay. The throttle control motor relay is ON/OFF controlled by the ECM. When the ignition switch is turned ON, the ECM sends an ON signal to throttle control motor relay and battery voltage is provided to the ECM. When the ignition switch is turned OFF, the ECM sends an OFF signal to throttle control motor relay and battery voltage is not provided to the ECM.

Possible Causes For P1126:
- Harness or connectors (Throttle control motor relay circuit is open)
- Throttle control motor relay


P0325 - Knock Sensor Circuit Malfunction

The knock sensor is attached to the cylinder block. It senses engine knocking using a piezoelectric element. A knocking vibration from the cylinder block is sensed as vibrational pressure. This pressure is converted into a voltage signal and sent to the Powertrain Control Module (PCM) or Electronic Control Module (ECM).

Possible Causes For P0325:
- Knock sensor circuit short to ground.
- Knock sensor circuit short to power.
- Knock sensor circuit open.
- Damaged knock sensor.
- Damaged PCM or ECM

Possible Solutions:
- Repair or resecure harness or connector
- Replace knock sensor Bank 1 (Bank 1 if applicable)
- Replace PCM or ECM

The P0325 DTC is a very common problem with Nissan vehicles. On most Nissan vehicles the knock sensor is located on top of the engine block.

OK THIS A SITUATION. THE P0100 IS A MASS AIR FLOW PROBLEM. THE P0325 IS A KNOCK SENSOR MALFUNCTION. AND THE P0733 IS A TRANSMISSION ISSUE. I DONT KNOW IF U HAVE A TRUST WORTHY MECHANIC BUT FOR THESE THREE FIXES U NEED ONE ESPECIALLY IF U ARE NOT CAPABLE OF THIS WORK. THESE PROBLEMS WILL CAUSE U POOR PERFORMANCE AND A HEADACHE. THESE PROBLEMS DEFINITELY NEED TO BE HANDLED ASAP!

Clean your mass air flow sensor with electrical contact cleaner. It's located between your air box and intake when it gets dirty it tricks your car into thinking it's getting less air than it is

If you're getting check engine light take it to Autozone and they'll read the code. On mine the Mass Air Flow sensor was the culprit. Engine codes suggested MAF, manifold vacuum leak, coils, injectors clogged. Mass Air Flow sensor cleaner did nothing. Ultimately I replaced each coil ($75 per cyl) but still conked out like yours. MAF cost $300 at the store, but found one online $97 took a gamble and replaced in 5 minutes. It really made a difference.

change the temp sensor

Nissan code:
P1444 Canister Purge Volume Control Solenoid Valve

Generic OBD II code:
DTC Codes - P0300-P0399 – Ignition System or Misfire
P0325 Knock Sensor 1 Circuit Malfunction (Bank 1 or Single Sensor)

I hopes this helps you.
Replace or fix these two items should do the trick.
It's hard to diagnose a car over a computer.