2002 Ford Explorer Explorer will crank over, but won't star

Hello -

To better assist you is your model just an Explorer or Sport or Sport Trac. Also please provide your engine size in liter and the 8th digit of your VIN.

Please go to Auto Zone (AZ) or O'Reilly's (OR) and use their tool check out program and get the code scanner. Check your codes, if you find something and you don't get it fixed and need to get back with us, please make sure you tell us exactly what the code was, number and all. Example, if the code was E0568 O2 Sensor bad. Then make sure you give us all of that.

Your Engine Coolant Sensor (ECT) can also prevent this if defective.

Hello -

Thanks for the info - please keep me posted.

Here is some info for you on the O2s

O2 Sensor Strategies: Unheated one- or two-wire O2 sensors on 1976 through early 1990s applications should be replaced every 30,000 to 50,000 miles to assure reliable performance. Heated 3 and 4-wire O2 sensors on mid-1980s through mid-1990s applications should be changed every 60,000 miles. On OBD II equipped vehicles, the recommended replacement interval is 100,000 miles. The O2 sensor's responsiveness and voltage output can diminish with age and exposure to certain contaminants in the exhaust such as lead, sulfur, silicone (coolant leaks) and phosphorus (oil burning). If the sensor becomes contaminated, it may not respond very quickly to changes in the air/fuel mixture causing a lag in the PCM's ability to control the air/fuel mixture.
The sensor's voltage output may decline giving a lower than normal reading. This may cause the PCM to react as if the fuel mixture were leaner than it really is resulting in an overly rich fuel mixture.