Location of ecm on 2004 honda pilot.

Possible causes Faulty Engine Control Module (ECM) Faulty ABS actuator and electric unit (control unit) Control Area Network (CAN) communication line Blown ECM fuses What does this mean? Tech notes The code means that the Anti-Lock Brake System (ABS) control unit has detected that there is a problem with the Engine Control Module (ECM). What does this mean? When is the code detected? Based on the signal from Engine Control Module (ECM), the Control Area Network (CAN)-Local Area Network (LAN) converter (CLC) judges that the engine control system is malfunctioning. Possible symptoms ABS Warning Light ON Scanner cannot access Engine Control Module (ECM) C1130 Infiniti Description ABS actuator and electric unit (control unit) and ECM exchange the engine signal with CAN communication line. Major engine components are malfunctioning.

Read more: https://www.engine-codes.com/c1130_infiniti.html

P1296 CHRYSLER - 5 Volt Reference Voltage Missing At Throttle Position Sensor
https://www.autocodes.com/p1296_chrysler.html

Tech notes
Adjusting the valves will usually fix this problem.
When is the code detected?
The control module monitors the crankshaft speed and has detected a misfire condition
Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Lack/loss of power
- Hard start
- Engine hesitation
P1399 Honda Description
When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the Crankshaft Position (CKP) sensor signal to vary, the Engine Control Module (ECM) can determine that a misfire is occurring.
- Valve clearance out of range

Reset oil service light Honda Pilot. From years: 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012.
How do you reset oil service light Honda Pilot. From years: 2003, 2004, 2005.

1. Turn off the engine. Press and hold the SELECT/RESET button in the instrument panel and turn the ignition switch to run (one position before starting).
2. Hold the button for at least 10 seconds, until the indicator resets.
3. Turn the ignition off and then start the engine to verify the indicator has been reset.

How to reset oil service light Honda Pilot. From years: 2006, 2007, 2008, 2009, 2010, 2011, 2012.
Resetting the Engine Oil Life Display if maintenance service is done by someone other than your dealer, reset the maintenance minder as
follows:

1. Turn the ignition switch to the ON (II) position.
2. Press the select/reset knob repeatedly until the engine oil life is displayed.
3. Press the select/reset knob for about 10 seconds. The engine oil life and the maintenance item code(s) will blink.
4. Press the select/reset knob for another 5 seconds. The maintenance item code(s) will disappear, and the engine oil life will reset to 100.

All information is taken from the Honda Pilot owners manual.

Looking at the data sheet it says for P0604 the location for the fault is the Engine Control Module (ECM) - RAM error, and the probable cause is the ECM. As you didn't say which engine I have given you the best answer I can, I hope it helps you

Error Code: P0505
Fault Location:
Idle Speed Control (ISC) System - Malfunction
Possible Cause:
-Wiring harness.
-Idle speed control (ISC) actuator/Idle air control valve (IAC) valve.
-Throttle valve tight/sticking.
-Engine control module (ECM).

Error Code: P0130
Fault:
Oxygen Sensor (O2S) 1, Bank 1 - Circuit Malfunction
Possible Cause:
Malfunction Indicator Lamp (MIL) Triggered on first occurrence.
-Wiring harness.
-Oxygen sensor (O2S).
-Engine control module (ECM).

Error Code: P0505
Fault:
Idle Speed Control (ISC) System - Malfunction
Possible Cause:
-Wiring harness.
-Idle speed control (ISC) actuator/Idle air control valve (IAC) valve.
-Throttle motor.
-Throttle valve tight/sticking.
-Engine control module (ECM).

Error Code: P0100
Fault Location:
-Mass Air Flow (MAF) Sensor/Volume Air Flow (VAF) Sensor - Circuit --Malfunction
Possible Cause:
-Wiring harness.
-Mass air flow (MAF) sensor.
-Volume air flow (VAF) sensor.
-Engine control module (ECM).

Error Code: P1491
Fault:
Exhaust Gas Recirculation (EGR) Valve Insufficient Lift
Possible Cause:
-Wiring harness.
-EGR Valve.
-ECM

Error Code:P1607
Fault:
-Engine Control Module (ECM)/Powertrain Control Module (PCM)

Error Code: P0966
Location:
-Pressure Control (PC) Solenoid B - Circuit Low
Possible Cause:
-Wiring short to earth.
-Pressure control (PC) solenoid.
-Engine control module (ECM)/Powertrain control module -(PCM)/Transmission control module (TCM) .

No it is not Catalytic Converter related. Your fuel tank pressure sensor must be disconnected or the wiring to it defective for the evaporative emission system.
P0453 HONDA - Fuel Tank Pressure Sensor High Voltagehttp://engine-codes.com/p0453_honda.htmlForum CodePossible causes- Fuel Tank Pressure sensor harness is open or shorted
- Fuel Tank Pressure sensor circuit poor electrical connection
- Fuel Tank Pressure Sensor
- Faulty Engine Control Module (ECM) When is the code detected?A high voltage signal from the fuel tank pressure sensor is sent to Engine Control Module (ECM).
P0450 - Evaporative Emission Control System Pressure Sensor Malfunctionhttp://engine-codes.com/p0450.htmlForum CodePossible causes- Evaporative Emission System (EVAP) Pressure sensor harness is open or shorted
- Evaporative Emission System (EVAP) Pressure sensor circuit poor electrical connection
- Faulty Evaporative Emission System (EVAP) Pressure Sensor
- Faulty Engine Control Module (ECM) When is the code detected?- An improper voltage signal from EVAP control system pressure sensor is sent to ECM.

P2647 VTEC Oil Pressure Switch Circuit High Voltage - With Automatic Transmission Basicallly the sensor has gone bad or an oil passage has become blocked.

**. Locate the Variable Timing Electronic Control (VTEC) pressure switch on the end of the cylinder head. Honda has had problems with the VTEC oil pressure switch, there is an updated part number for the vehicle (37250-PNE-G01). On this vehicle the VTEC oil pressure switch can fail at any RPM.
2. The VTEC oil switch is normally closed, and grounds the reference voltage from the Engine Control Module (ECM) on the Blue/Black (BLU/BLK) wire. If the code sets at idle - 2500 RPM - and the Brown/Yellow wire has a good ground, then suspect a faulty VTEC oil pressure switch.
3. At approximately 2500-4000 RPM and when driving the vehicle, the VTEC system should turn on. To turn on the system, the ECM energizes the VTEC Solenoid valve and it allows oil pressure into the intake valve rocker arms, the oil pressure opens the VTEC oil pressure switch so the Engine Control Module (ECM) can verify that the VTEC did turn on correctly.
4. The code will set at idle to 2500 RPM if the reference voltage is not grounded. The code will set above 2500-4000 RPM if the VTEC oil switch does not open.
5. If the code sets at 2500-4000 RPM or higher, the problem can be a low oil level or pressure, or a malfunction in the VTEC assembly.
Potential Causes: Low Engine Oil
Plugged Oil Passage
Insufficient Oil Pressure
Plugged Oil Screen
Insufficient Oil Volume
Malfunctioning VTEC Oil Pressure Switch
Defective VTEC Solenoid