It's yellow coloured with an engine icon with the word "CHECK" that lights up when you turn the ignition key to "On" position, and it goes off again when the ECU finds that everything is in good order (to let you know that you can start the engine now). Look at the pic above, it's the one near the number "6" of the tachometer, below the oil pressure (alladin lamp) and battery indicator light.Always start the engine only after the checklight goes off.
If your checklight lights up anytime while the engine is running, it means there could be a faulty or disconnected sensor. The ECU detects errors on the sensors, and lights up the checklight to warn the driver of the fault. It's time to do the "Check Engine Light Diagnostic". These steps apply to Honda cars only. I don't know how it's done on other cars. Here it is:
Find the ECU cover on the passenger side, it's located on the left-hand-side underneath the glove box.
Remove the ECU cover. That baby there is the ECU a.k.a the "computer box". It's the brain of your car. No, we're not gonna talk about that. I'll tell about ECUs later (if I'm not too lazy to write). What we're looking for here are the service connectors wrapped in green protective rubber covering. Found it? Good.
Inside the connector cover, are two connectors. One is a two-pin, and the other one a three-pin connector. Take out the two-pin connector. (Careful not to break the wires).
Get a piece of old speaker wire (or any wire) and connect the two pins together. Alternatively, you can use paper clip for that purpose.
Now, turn your ignition switch to "ON" position (don't start the engine). If the fault is still around, your checklight will start blinking. There 2 types of blinks - short blinks, & long blinks. A short blink represents a value of 1, and a long blink represents a value of 10.
Count the blinks. You need to do some maths now. For example: 2 long blinks + 2 short blinks = (2 x 20) + (2 x 1) = fault code = 22. Now look up the fault code table below. Voila! in our case, fault code 22 = "VTEC oil pressure switch circuit".
Honda ECU Error Codes
0 = Faulty ECU (no signal)
1 = Oxygen sensor or circuit.
2 = Faulty ECU
3 & 5 = Manifold Absolute Pressure (MAP) sensor or circuit.
4 = Crank angle sensor or circuit
6 = Coolant temperature sensor or circuit
7 = Throttle Position Sensor (TPS) or circuit.
8 = TDC position/crank angle sensor or circuit.
9 = Crank angle sensor or circuit or Distributor
10 = Intake air temperature sensor or circuit.
11 = No particular symptom shown or system does not operate - faulty ECU
12 = Exhaust gas recirculation (EGR) failure
13 = Atmospheric pressure sensor circuit.
14 = Electronic air control valve (EACV)
15 = No ignition output signal - possible faulty igniter.
16 = Fuel injector circuit.
17 = Vehicle speed sensor or circuit (VSS)
19 = Lock-up control solenoid valve (automatic transmission)
20 = Electronic load detector - possible open or grounded circuit in ECU wiring.
21 = VTEC solenoid valve circuit
22 = VTEC oil pressure switch circuit
23 = Knock sensor 30 = A/T control unit ECM fuel injection signal "A" (Accord & Prelude)
31 = A/T control unit ECM fuel injection signal "B" (Accord & Prelude)
36 = TCS traction control unit or wiring or ecu
41 = Heated oxygen sensor - heater circuit.
43 = Fuel supply system circuit (except D15Z1 engine)
45 = Fuel system out of range - rich or lean
48 = Heated oxygen sensor circuit (D15Z1 engine)
50 = Mass airflow sensor.
61 = Front oxygen sensor response slow.
63 = Rear oxygen sensor circuit voltage out of range.
65 = Rear oxygen sensor circuit malfunction.
67 = Catalyic converter efficency low.
70 = Automatic Transaxle problem.
71 = through,
76 Cylinder misfires
80 = Insufficient EGR flow
86 = Engine coolant temperature sensor circuit.
92 = Evaporative emission purge valve problem
So guys, the next time you're caught in a checklight situation, you know what to do. Good Luck!
