post #16 of Old 07-13-2010, 09:01 PM
tr0mbley
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ProjectWhiteTJ, did the crankshaft position sensor fix your p030* problem? Thanks in advance.

I first got the flashing check engine light on the highway one day. It went away immediately. Took it to Autozone and the scan turned up P0300, P0301, P0303, P0304, P0306. I changed plugs, still got the codes. Changed the plug wires, distributor cap, rotor. Codes were gone for about a week and a half (long enough to pass inspection ).

Then... I was driving home on the highway again today, and the flashing CEL comes on again but stays on this time, which is way more stressful. I did my best to check every single rubber hose under the hood, but honestly, it's hard to understand what the hell all the vacuum lines do. I wouldn't be surprised if there was a freaking vacuum hose connected to the brake pads, steering wheel, spare tire, turn signal......etc. I found nothing out of the norm, whatever that was. Couldn't hear any obvious whistling (though there is a fan blowing the hell out the engine bay all the time so it makes it hard to hear).

I guess it's time to start trading out sensors. Seems like there would be a more specific error for the O2 or crankshaft sensor? Isn't there a better way to solve this besides throwing money at every electronic part under the hood? Even so, I'll probably start with the O2 sensor because my mpg seems a little low and the engine feels like it is running rough (though I really have nothing to compare it to as this is my first TJ with an I6). If I just take out the O2 sensor will it look "dirty" or burnt out" if it is - in fact - bad? It also starts hard on cold startups. Sometimes I actually stop turning it over because it takes so long. Warm startups are fine.

Thanks for the update/answers.

Bob

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post #17 of Old 07-14-2010, 01:51 PM
tr0mbley
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Unplugged the header O2 sensor this morning. The car ran a little better than usual, but I burned through 2.06 gallons of gas over 18.6 miles. Not good. I plugged the sensor back up, and the performance seemed to remain the same. Hopefully gas consumption will return to normal levels. I will try unplugging the post-cat O2 sensor this evening and see what that does. Still have the codes.
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post #18 of Old 07-15-2010, 05:24 PM
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Update: Unplugged the post-cat O2 sensor, performance seemed about the same. Reconnected it later that evening and the CEL remained on. Went out to the car this morning to start it, and it was still on. Went out for ice cream later on, and the CEL was off. I have no idea what is causing it, but it seems electrical to me. I bought a Bosch exact fit O2 sensor for $62 and will be replacing it tonight.
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post #19 of Old 07-20-2010, 12:05 PM
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Update: The upstream O2 sensor was replaced about 5 days ago and the idle, cold start, overall performance, and gas mileage all seem to be improved. CEL is still off. Looks like this was the fix. I may proactively replace the downstream sensor to be sure. As far as I can tell, I am getting about 16.5 mpg on this tank.
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post #20 of Old 12-11-2013, 03:35 PM
goose0823
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I have been having all these problem replaced the crank position sensor and it helped a lot... I couldn't get the old o2 sensors off so I havnt replaced them yet... I just got the blinking engine light and from what it sounds like I and yours needs a tune up plugs wires cap button whole nine yards
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post #21 of Old 12-11-2013, 04:10 PM
jeeper01ca
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I have had my check engine light blinking whenever I drive over 80 km/hm I changed my O2 sensor and never came back and no check engine errors at all.

http://groups.msn.com/TJeeP4-0L
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post #22 of Old 12-11-2013, 08:12 PM
Knuckelhead
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Quote:
Originally Posted by goose0823 View Post
I have been having all these problem replaced the crank position sensor and it helped a lot... I couldn't get the old o2 sensors off so I havnt replaced them yet... I just got the blinking engine light and from what it sounds like I and yours needs a tune up plugs wires cap button whole nine yards

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post #23 of Old 10-05-2014, 09:59 AM
john1954
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no answers to 303 code for my 2003 Jeep Liberty, I have changed plugs,coil packs crank sensor cam sensor fuel rail (leaking) new breather hoses. Problem started as 1391 crank sensor replaced along with all above and cleaned throttle body. 303 code came on about 30 miles later. Anybody?
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post #24 of Old 10-05-2014, 10:00 AM
john1954
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2003 jeep liberty 303 code

no answers to 303 code for my 2003 Jeep Liberty, I have changed plugs,coil packs crank sensor cam sensor fuel rail (leaking) new breather hoses. Problem started as 1391 crank sensor replaced along with all above and cleaned throttle body. 303 code came on about 30 miles later. Anybody?
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