Please read disclaimer before continuing.
PETROL ENGINE SENSORS click here for diesel
This list and symptoms is for petrol engines only, Engine Management Light will be on if sensor fails outside its normal working parameters, example coolant sensor tells ECU coolant is 200ºC
You really need a EOBD scan tool to test these sensors but I have listed methods for some with a multimeter.
| SENSOR TYPE | NORMAL SYMPTOMS | HOW TO TEST |
|---|---|---|
| CRANKSHAFT (CPS) | NON START, OCCASIONALLY MAY CUT-OUT AND RESTART | |
| CAMSHAFT SENSOR | NORMALLY NONSTART, ECU MAY GUESS CAMSHAFT POSOSITON | |
| COOLANT SENSOR | MAY BE NONSTART IF SENSOR TELLS ECU WRONG TEMPERATURE | |
| AIR FLOW SENSOR | NORMALLY WILL START ECU WILL USE DEFALT, WILL RUN ROUGH | |
| MANIFOLD ABSOLUTE PRESSURE (MAP) | NORMALLY WILL START ECU WILL USE DEFALT, WILL RUN ROUGH | |
| THROTTLE PEDAL | WON'T REV, MAY BE OK AGAIN AFTER RE-STARTING | |
| AIR TEMPERATURE | MAY UPSET STARTING AND RUNNING SLIGHTLY | |
| ATMOSPHERIC | MAY UPSET STARTING AND RUNNING SLIGHTLY | |
| KNOCK (PINKING) | MAY LOOSE POWER IF ECU RETARDS IGNITION TIMING |