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Thread: Q: Can the O2 sensor keep the engine from starting?

  1. #1

    Question Q: Can the O2 sensor keep the engine from starting?

    I have a 1995 zetec engine. I drove it home and 45 min later it would not start. It would turn over but not fire off. The next morning after 3 attemptes it started. Could the o2 sensor do that?
    Last edited by dbeale; 11-02-2006 at 10:21 PM.

  2. #2

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    Quote Originally Posted by dbeale View Post
    I have a 2001 zetec engine. I drove it home and 45 min later it would not start. It would turn over but not fire off. The next morning after 3 attemptes it started. Could the o2 sensor do that?
    Maybe. Get the code(s) read at Autozone or Advance (free service) and post the exact code(s) here.

  3. #3
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    The o2 should not keep an engine from running.If it's bad /not there/or just reading way off it sends the car into a default mode that would still alow it to run.

  4. #4

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    Quote Originally Posted by Tony2005 View Post
    Maybe. Get the code(s) read at Autozone or Advance (free service) and post the exact code(s) here.
    I have a cel tester. It gave code 10 snap throttle; 538cyl bal test fail restart and 172 EGO not switching, lean bank exh-bank. I don't understand these. It has been starting now, but I'm not sure I can trust it away from the house, as I don't know why it suddenly would not start after sitting 30 munites last friday. There is no current CEL light but it smells of gasoline. i.e rich. The KOEO gave not errors, only in the running KOER state.

  5. #5
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    No,
    The 02 is not used at all during starting. The fuel and timing come from a look up table until the engine enters closed loop operation.

    No start is caused by lack (or excessive) fuel, no spark (or timing), or loss of compression.

    Intermittent starting is usually electrical (cam/crank sensor). Also, if it starts fine cold but not hot then a bad ECT sensor could be causing a rich condition during hot start and run.

    jeff
    Last edited by mercman; 11-02-2006 at 10:00 PM. Reason: You did say 2001 zetec
    have you fixed your ford lately?

  6. #6

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    My car is a 1995 Zetec DOHC. I have replaced the EGR vlv, throttle sensor, flow sensor, trans overhauled, water pump(four times), timimg belt& pullies, & resently plugs&wires, and last fixed bad wires & connector to the crank pickup sensor. Last problem was the starter replacement. Boy what a job that was! I'm about ready to drive it off the clift. Wonder if 'made in Mexico' has anything to do with it? So what is "code 10 snap throttle"? I originally said 2001, I meant 1995. I at the sametime had key problems with a 2001 impala passlock junk $195. worth.
    Last edited by dbeale; 11-02-2006 at 10:19 PM.

  7. #7
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    If I remember my Ford STAR test it is probably the No Goose code (during the KOER test you are supposed to floor the throttle quickly when prompted by the PCM). Donít worry about it now.

    Next time you get the no start check for spark, if it is missing check your crank sensor wiring. The crank and cam sensors produce a low output and must use good shielded cable for signal transmission. The garden variety solid or stranded speaker wire will not do here.
    jeff
    have you fixed your ford lately?

  8. #8

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    It started this morning then immediately died, but did restart. While driving to work, the cel came on. Checking the cel I got '172 EGO not switching, lean exh-bank 1' & '225 No Knock signal during self test'. Is EGO= exhaust gas oxygen sensor? And what is 225 no knock signal?

  9. #9
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    the no start may be caused by a faulty cam sensor. if the cam sensor goes bad the system falls into whats called Failure Mode Effects Management (FMEM) once in this mode the car will still start but it may take up to three tries (like yours did) to find the right "default" spark setting. test the cam sensor with an Ohm meter and tello us what you get. its located on the firewall back corner of the engine near the end of the fuel rail.

    EGO does=Exhaust Gas Oxygen
    the computer thinks its not switching and staying lean. could be a bad sensor or you really are running too lean. ta bad sensor wont keep it from starting. if your running too lean your not getting enough fuel. could be caused by several things including a weak fuel pump, clogged injectors, bad fuel pressure regulator, leak in one of your fuel lines.

    No Knock Signal.
    the computer did not recieve a signal from the knock sensor. could be something as simple as faulty wiring or it could be (although not likely) a faulty sensor. check the wiring for the knock sensor.
    TZT Performance http://www.tztperformance.com/
    officially a troll. '93 3000GT VR4 #2229/2595

    '00 Black SVTC #391 - sold 5/1/10
    '97 GL Turbo Zetec - gone

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