My service engine light soon came on last night driving home in the rain. I drive a 2002 ford explorer suv .?

Question

The diagnosis was Po156, the book says it is a oxygen sensor but the mechanic said he would start with a fuel filter and fuel pump. I got a second opinion and he said drive it a while it may go out because I may have bad gas or could have not got my gas cap on right before. Which do I go with?

Answer 1

Changing the fuel filter is cheap the pump is not you can also get the light if the cap is not on right if it is the oxgen sensor your fuel milage will suffer and if it was just some water getting onto your distributor cap or spark plug wires it will go away after it drys.

Answer 2

It could also be nothing. My VW's  light comes on automatically every 50k or 80k miles, just to remind me of a checkup. I would just try resetting the oxygen sensor and then if there is really a problem it will come back on immediately.

On mine it's a small black recessed button that you can push with a nail or pencil. Hold the button in for 10 secs and you're good to go.

Answer 3

Im with the second guy on this. The oxygen sensor is picking up a reading that may be just a little moisture in the fuel or a wet connection on the sensor (located on the tailpipe under the car) Its always a good idea to keep a recent fuel filter on any car but it could be nothing. Check your gas cap to make sure the seal is good.

Answer 4

What makes the mechanic think the fuel pump is bad?

Did he physically bust out a pressure gauge and check that already?

If not, get another opinion.

As for resetting codes, the other posters like to work too much.

Just pull the PCM fuse in the underhood fuse box and put it back in and the computer is reset.

Answer 5

if the fuel pump was bad, you would,nt be driving it home and if the gas filter was clogged, it would,nt start up, besides the gas filter would,nt make the light come on. i would say go with the code it,s throwing and replace the 02 sensor, but unhook the battery first.

Answer 6

Opinion #2 makes the most sense. Drive it a few days after your next gas fill up. If the warning is still there then perhaps your oxygen sensor has gone bad. It can't be your fuel pump or fuel filter or you would be occasionally losing power at highway speeds due to fuel starvation. Change the fuel filter if you like, it can't hurt and they're inexpensive.

Answer 7

I agree with Chris R.  Drive it through the next tank of gas.  If the light is still on disconnect the battery for 10 minutes.  Hook it back up and start the car, but make sure you let it run for 10 minutes before shutting it off so the computer can reset itself.  When you disconnect the battery the computer needs to reset or the car may run rough.  That should clear the error and turn the light off.  If it comes back on then you probably need an oxygen sensor.  It is the most common cause for the light.

Answer 8

You don't need a fuel filter or fuel pump.  I would ride out the tank and see what happens on the next.  To reset the Check Engine Light, pull the positive lead on the battery and the reattach.  You will most likely need a new O Sensor ($100 bucks).

Answer 9

find new mechanic....no reason on earth to replace pump,,,maby filter if ox sensor doesn't fix it...really may be bad gas/loose gas cap...i agree with other guy...fill tank from different station and make sure gas cap tight...reset lite...[whoever scanned it should have done it]