Will bad oxygen sensors show as a engine light?

Ryan95gt · 04-09-2001, 11:10 PM

I was wondering if you have bad oxygen sernor or sensors does it show as a engine light? I failed emissions and I may suspect a bad o2 sensor but I have no engine light on.

84_GT350 · 04-10-2001, 12:20 AM

Usually, yes. I hestate to say always though. Have you considered things like malfunctioning emissions equipment or clogged cats? It could something pretty simple.

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1984 1/2 GT350 (#842 Hatchback w/ T-tops), 302HO, Comp cams Xtreme Energy cam, Carter 625cfm carb, Weiand Stealth intake, MSD distributor, MSD coil, FMS 9mm wires, 1 5/8" MAC unequal shorties, 2 1/2" MAC Prochamber H-pipe, Flowmaster 2 chambers, KYBs, 16"x8" 4 lug Cobra Rs, Falken 245/45ZR16s

04-10-2001, 03:00 AM

If there's carbon built up on the oxygen sensor it probably won't send a signal but it will read incorrectly. What did you fail in? CO and HC?

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'84 Mustang 5.0 T5, FMS aluminum radiator & 180* thermostat, 1 5/8 shortys/2.5" duals, '88 GT tail lights and wheels, Holley 4160 4 BBL, smog pump idler, now with hi-po collapsed lifters in #3 or #4

Ryan95gt · 04-10-2001, 08:45 PM

I failed for nox, double the allowed limit. Car has 62k, engine pretty much stock, recent tune up,I only put about 2k on it in the last year. Has mac cat h-pipe.

COME CORRECT · 04-13-2001, 11:40 PM

Yes the check engine will come on. It will soon start wander around when idling and no settle in once it gets warm. Replace them with NASCAR sensors.

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PALADIN
"COME CORRECT"

2FastLX · 04-14-2001, 01:36 AM

Where do you get NASCAR sensors??

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ICQ# 42269241
Indiana Stangers Association
Buy your parts here

XOCHXXIII · 04-14-2001, 02:32 AM

a bad oxygen sensor will not trigger the chech engine light,i speak from personal experience,i had a 87 lx that had hesitation problems and backfiring,i went ahead and did a code scan,the scan detected the problem with the oxygen sensor,turned out the ceramic in the sensors were broken,once i replaced them it ran smooth again.hope this helps.

dinomite · 04-14-2001, 11:32 AM

No, most of the time the check engine light means nothing more than a bad oxygen sensor. Toss some new one in, can't recommend a brand though, OEM?

COME CORRECT · 04-17-2001, 01:52 AM

I went to NAPA and used the same sensor they put in the sprint cars for ford engines. I changed them because of the fuel I used. when I start to see trouble of any kind I've learned to monitor the O2 sensors. This is the case when using leaded race fuels. some may disagree but it works for me.

------------------
PALADIN
"COME CORRECT"

04-09-2001, 11:10 PM	#1
Ryan95gt Registered Member Join Date: Apr 2001 Location: east hartford ct usa Posts: 16	Will bad oxygen sensors show as a engine light? I was wondering if you have bad oxygen sernor or sensors does it show as a engine light? I failed emissions and I may suspect a bad o2 sensor but I have no engine light on.

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04-10-2001, 12:20 AM	#2
84_GT350 Registered Member Join Date: Apr 1999 Location: Overland Park, KS, USA Posts: 1,631	Usually, yes. I hestate to say always though. Have you considered things like malfunctioning emissions equipment or clogged cats? It could something pretty simple. ------------------ 1984 1/2 GT350 (#842 Hatchback w/ T-tops), 302HO, Comp cams Xtreme Energy cam, Carter 625cfm carb, Weiand Stealth intake, MSD distributor, MSD coil, FMS 9mm wires, 1 5/8" MAC unequal shorties, 2 1/2" MAC Prochamber H-pipe, Flowmaster 2 chambers, KYBs, 16"x8" 4 lug Cobra Rs, Falken 245/45ZR16s

04-10-2001, 03:00 AM	#3
84stangLX Guest Posts: n/a	If there's carbon built up on the oxygen sensor it probably won't send a signal but it will read incorrectly. What did you fail in? CO and HC? ------------------ '84 Mustang 5.0 T5, FMS aluminum radiator & 180* thermostat, 1 5/8 shortys/2.5" duals, '88 GT tail lights and wheels, Holley 4160 4 BBL, smog pump idler, now with hi-po collapsed lifters in #3 or #4

04-10-2001, 08:45 PM	#4
Ryan95gt Registered Member Join Date: Apr 2001 Location: east hartford ct usa Posts: 16	I failed for nox, double the allowed limit. Car has 62k, engine pretty much stock, recent tune up,I only put about 2k on it in the last year. Has mac cat h-pipe.

04-13-2001, 11:40 PM	#5
COME CORRECT Registered Member Join Date: Jul 1999 Location: Headed EAST in 5 days Posts: 252	Yes the check engine will come on. It will soon start wander around when idling and no settle in once it gets warm. Replace them with NASCAR sensors. ------------------ PALADIN "COME CORRECT"

04-14-2001, 01:36 AM	#6
2FastLX The Photoshop Guru Join Date: Feb 2001 Location: Mecca, Indiana Posts: 1,419	Where do you get NASCAR sensors?? ------------------ ICQ# 42269241 Indiana Stangers Association Buy your parts here

04-14-2001, 02:32 AM	#7
XOCHXXIII Registered Member Join Date: Mar 2001 Location: BRIGHTON,CO USA Posts: 6	a bad oxygen sensor will not trigger the chech engine light,i speak from personal experience,i had a 87 lx that had hesitation problems and backfiring,i went ahead and did a code scan,the scan detected the problem with the oxygen sensor,turned out the ceramic in the sensors were broken,once i replaced them it ran smooth again.hope this helps.

04-14-2001, 11:32 AM	#8
dinomite The Dude Join Date: Feb 2001 Location: Arlington, VA Posts: 1,262	No, most of the time the check engine light means nothing more than a bad oxygen sensor. Toss some new one in, can't recommend a brand though, OEM?

04-17-2001, 01:52 AM	#9
COME CORRECT Registered Member Join Date: Jul 1999 Location: Headed EAST in 5 days Posts: 252	I went to NAPA and used the same sensor they put in the sprint cars for ford engines. I changed them because of the fuel I used. when I start to see trouble of any kind I've learned to monitor the O2 sensors. This is the case when using leaded race fuels. some may disagree but it works for me. ------------------ PALADIN "COME CORRECT"