Engine light refuses o go out

180

Asked by Apr 11, 2013 at 11:00 PM about the 2002 Hyundai Elantra GT

Question type: Maintenance & Repair

The engine light went on and was triggered by a 'faulty' oxygen sensor.  The upstream sensor was replaced, twice
with a generic sensor, then with a hyundai sensor, the downstream sensor was also replaced twice.  The car has
been in the shop almost continuously for 3 weeks, the engine light is reset and after all the corrections to what the
code stated was wrong, after driving 25-30 miles, the engine light goes on again.  I take it in to the garage again and
it's the same code for the oxygen sensor.  It has been through 3 diagnostic machines, each one more sophisticated
than the last.  Each one says it's the oxygen sensor.  What to do now?

36 Answers

102,815

You connected three sensors. You can assume that they should have been good. Has anyone checked the wires that all three have been connected to?

6 of 6 people found this helpful.

black tape solution~

32 of 32 people found this helpful.
180

Thanks for your answers, but the car needs an inspection and none of the inspection places will inspect with the engine light on and I can't afford to buy another car.

5 of 5 people found this helpful.

no, Lilyvt jokes about black tape to stop you from looking at it aside, go to one of the big auto parts stores and ask them to run a diagnostic check (for free, of course) they'll produce some numbers for us like P102 for example, then we'd have a chance of helping you~

1 of 1 people found this helpful.
102,815

Did anyone look at the wires? You don't need another scan for trouble codes. Typical code is code P0141 which may mean that one or more of the following has happened: open or short to ground in the wiring harness - O2 heater circuit wiring high resistance - O2 heater element resistance is high - Internal short or open in the heater element

2 of 2 people found this helpful.
264,265

I searched the Hyundai forums and in '01 there was a recall on the exhaust manifold, I see you have an 2002. But if you still have a CEL, others have had the same issue and it means you probably have an exhaust leak, like a rusty flex pipe. You have to remove the heat shield to really look at the manifold. This will cause air to enter the system tripping the O2's to detect an issue. Cracks are found in between the "fingers" of the manifold... like your hand "fingers". Could also be a gasket, but look for cracks. HTH's

3 of 3 people found this helpful.
180

The upstream oxygen sensor was replaced three times (twice with after market sensors from the car parts store and one from the dealership), the downstream sensor was replaced twice, the wires were cleaned out, the flex pipe was replaced, seafoam engine cleaner was added, premium gas was used for two cycles. It has been diagnosed at four different places, each more sophisticated than the previous. It's always the same answer, the oxygen sensor code P. the engine light is reset and every time it goes on after about 25 to 30 miles of being driven. At this point, none of the garages I've even to has any idea why. BUT, the car has to be inspected to drive and it fails. The car runs great, passes all the safety tests, has had the work done to correct what was supposed to be wrong and yet still fails. This thing is making me very unhappy, besides costing a fortune.

13 of 13 people found this helpful.

sell this one and buy a Toyota, they're unparalleled in reliability~

4 of 4 people found this helpful.
105

Lilyvt: I can sympathise with you: I related your problem to my Chilean wife, she said: "Take the bulb out". Joking aside, she's probably right. If the engine is fine for oil, coolants etc, why worry about it?. This is in-built "Must Use Agency ...(wait for it) ...Experts". They are "board changers"....Not Experts. They probably know a little more than you do. I had this scenario years ago: Basically, after plugging in to the "Big Computer" it states: "Change board X" "Change sensor B".....Note...it is boards & sensors they change... FIVE MINUTE JOBS. And then they charge the earth . They DO NOT, EVER, RECTIFY an actual physical problem with your engine! For a start, they'd have to get their hands dirty So, the electronic technology is crap.....the manufacturers are responding to the sellers of their vehicles......Get the vehicles back in for maintenence....something we can charge for. Believe me: Engines these days are pretty indestructable. They have to be: Otherwise, how can you even sell more than one example of a model. ?Mmm? Electronics are fine.....but when you couple them with a desire to make money...it's a doddle to in-build "self-destruct" features.....Not the engine of course: Just the "lights" Am I making sense?

4 of 4 people found this helpful.
125

I HAVE A 2003 HYUNDAI ELANTRA THROWING A CODE PO 133. I THINK THE GUY WHO WANTS YOU TO BUY A TOYOTA HAS THE RIGHT IDEA BECAUSE THEY DON'T HAVE WEIRD PROBLEMS LIKE THIS, BUT I THINK I'M GOING TO CHECK THE SENSOR GROUND AND ALSO MANIFOLD AND FLEX PIPE LEAKS BECAUSE THE CAR'S ALREADY A COMEBACK AND I HAVE TO FIX IT.

1 of 1 people found this helpful.
125

ps If anyone has the real answer to code PO 133 0/2 SLOW RESPONSE IT WOULD BE APPRECIATED ALREADY PUT NEW 0/2 SENSOR

2 of 2 people found this helpful.

these heated O2 sensors DO need solid 12 volts...properly grounded for their heaters~ (a failure point)....so test the voltage for the heated sensor~

1 of 1 people found this helpful.
2,555

black tape? really... buy a Toyota? really... how about buy American and support americans! wow judgeroy... amazing !

2 of 2 people found this helpful.

Did I stress the importance of the GROUND, in this whole affair....what started out as a solid connection quickly becomes 'brown' power for the delicate sensors...the O2 bein' the one in trouble...that's why I suggest that you TEST the voltage at the sensor....these are actually quite a delicate affair and are quite fussy....that's why the light ain't goin' off~....power is "brown" via a bad ground....with a wire brush, you must undo the main 1/0 lug and place where it bolts and wirebrush it to assure full 300 cold crankin' amps thru there~ reset the trouble codes with a fifteen dollar scanner~

1 of 1 people found this helpful.

jjmtuttle, punch my smilin' face and send me a PM...we can talk about the air density in China and our willing policy of handing our keys to the castle, because the money men refuse to keep their money here in the US~ Detroit makes watches....no one needs a watch these days~

2 of 2 people found this helpful.
125

THANK YOU JUDGE ROY, I PLANNED ON DOING THAT AFTER THE HOLIDAYS. HOPEFULLY I CAN MAKE THE CUSTOMER HAPPY WITHOUT MORE MONEY BEING SPENT. I AGREE WITH YOU ON TOYOTAS, WHEN AMERICA MAKES A COMPARABLE CAR, ILL BUY ONE, BUT RIGHT NOW ALL ILL DRIVE IS TOYOTA. SINCERELY- 35 YEAR ASE MECHANIC PS- I'VE SEEN THEM ALL AND WHAT THEY DO.

4 of 4 people found this helpful.
125

as soon as i have a definite answer to this problem I will post it. hopefully it will help Hyundai owners.

2 of 2 people found this helpful.

Toyota had a NUMI facility in Fremont, for a while....Tesla bought the plant~ there was an ad where Hyundai was following a Honda and asserting their car was the same in every way except the price....well now it's time to meet the maker (or mechanic) who finds the cheap construction and short-cuts that make more work (turning the front brake rotors) is an example as the mechanic must hire a Grizzly Grinder...and run the motor to turn the rotors...they cannot be removed without taking the axles out....can speak from experience may be cheaper for you.......at first~

2,555

after reading some of your comments (fixes) and seeing your garage lol I would rather not waste my time. I just don't see it going well but I thank you for the invite... take care

1 of 1 people found this helpful.

You folks are ALL beautiful people and I wish you the happiest of holidays (no excuse for having too many sugary things to take to your tooth with a hammer and chisel)....but the body craves this chocolate...has special effects on Women....and causes one to have a HAPPY HOLIDAY~~~:)

125

the purpose of this forum is to find solutions to problems.not to criticize each other.thanks judge roy i dont see were jim contributes much.or is he looking for a solution i dont know.

1 of 1 people found this helpful.
2,555

if I cant help I don't answer... I move on no need to waste peoples time or knock there car down... the black tape remark made me read more and after reading more comments like that I did lower my self to his level and I shouldn't have. but when you Dog American products and haven't owned one for yrs maybe you should think twice. people like that are the ones that hurt ALL American brand name products. anyway Happy New Year.. and all be safe in what ever you drive.. hopefully 1 of the American big 3 lol

5

Can one of you guys summarize what would be the steps to handling this? I have been having this problem for my 2003 for 5 years now, and the garage just resets it and I have to drive it around, but I got one of the O2 sensors fixed last year and it turned on 15 minutes after my inspection.

if they are three wire "heated" 02 sensors. ..this device must have a steady 12.5 volts to operate successfully~ as I have asserted already wirebrush the main 1/0 cable as it attaches to the ground and the ground too...to assure a solid connection to the chassis and components that it serves~

1 of 1 people found this helpful.

with an fifteen dollar OBD-II scanner read then RESET the Codes~

2 of 2 people found this helpful.
125

the ground is control by the ecm on that car for the o/2 looked for a exhaust leak found it was good no vacuum leaks. but the rear 0/2 heater wire was hitting .the cv axel t/b was dirty , plug gap 7grand loose maybe thats it .

2 of 2 people found this helpful.
40

I'm having the same problem. 2005 Elantra GT sedan. The codes are P0171, P2243 and P0133. I've bought and returned an aftermarket sensor, and yesterday bought and installed an OEM sensor. I'm in it $110 for a repair shop diagnostic and $188 for OEM sensor, which they recommended. I have an appointment to spend another $125 for a dealership diagnostic tomorrow. I have to get it smogged to get it registered (California). Where is the 1/0 lug?!?!

4 of 4 people found this helpful.
125

never figured that elantra out .sent her to the dealer figured they made it they can fix it.but if you have po171 system lean you might have a vacuum leak.

replace cracking and bloated butyl rubber (coal tar and chewing gum) with silicone rubber hoses...they are ten times the cost but worth every penny~

40

@wizzbang: Yeah, I've read that before. Hopefully the dealership can diagnose it correctly. I think it's either the harness, cracked manifold or vacuum leak. It does sputter sometimes on acceleration.

10

Suffering owner of a 2002 money pit of questionable reliability. 2002 Hyundai Elantra GT hatch 5sp. Check engine light since day 3 of ownership (used, 155k). Front (r) axle replacement caused a TCM light to come on. Then the check engine light was run for codes: 10! My favorite was the SUPER COMMON rpm fluctuation. Up & down 1200 to 3000. Then to constant 3000. Then to constant 5000...5500! * Intake Manifold gasket!! $240 repair. Drive-able again. I bought it for 1400 and have had the recall CONTROL ARMS done after the left wheel nearly fell off! Local and low speed! I'M ALIVE! They added a subframe as well ($1500 to Hyundai Corporation) I would have taken the $1500 and a $500 "have a nice bus ride home" payment. Personally, I've invested about $2000 into the car myself. Still needs shocks. THUNK! Codes are still on. AC doesn't work. Front headlight is missing a clip: bounces at the drivers. Rear hatch supports failing. Brakes? Just plain SUCK-ASS DESIGN! Overall, the car will cost me over $3000 for a car that's not worth more than $2000 on a sunny day. And to think, I SOLD MY 98 TOYOTA T-100, SR5, extracab, auto, 4wd... for THIS? I should be in a padded room drinking from a sippy cup!

1 of 1 people found this helpful.
20

Does it make any sense that a dirty IAC could throw an oxygen sensor code? Apparently a misfire will also trigger the O2 sensor code. I got code 0139 "oxygen sensor slow response" on my 2006 Elantra GT hatchback (XD) and was puzzled since I had replaced both sensors a couple years ago to avoid having them get stuck. Thought maybe some anti-seize lube had contaminated the tips, but decided I'd try something else first. Acceleration seemed harsher and louder than in the past, but I could not find an exhaust leak on cursory examination. I was also experiencing rough erratic idle that fuel system cleaner did not correct (worse with AC on, better in neutral). So I took apart and cleaned the idle air control valve (also disassembled throttle body, but TB was already clean from holding it open and spraying it out last year). Since I had the air intake apart anyway I removed the mass air flow sensor and sprayed the wires with MAF cleaner. Replaced the TB and IAC gaskets. I've been driving a lot and no more check engine light since then. I am wondering if these now clean parts are compensating for the role of a bad O2 sensor, or if the problem is actually fixed. I read that the idle problem on Elantras can also be caused by a bad fuel pressure regulator which on 2006 is inside the fuel tank with the fuel pump and fuel filter but which on earlier models may be under the hood.

2 of 2 people found this helpful.

good morning everyone. I happen to have a 05 Hyundai elantra with the 2.0L. code p0420 has appeared. I monitored o2 sensor readings and sensor 1 is reading 2.0-1.7 volts and sensor 2 is reading 0.4 to 0.7 volts. has anyone ever heard of an o2 sensor reading more than 1 volt? and does anyone have any direction to go with this? thanks

10

buy american? Only some Fords are made in the USA all GM made in China

1 of 1 people found this helpful.

I had a code for the oxygen sensor and after looking for a long time, found out it was a small crack right down the middle of my exhaust header.

I replaced both convertors twice, many o2 sensors and in a few weeks or months lite back on. a service manager fo hyundai in austrailia finally gave me the soution, if you drive conservatively the ecu keeps changing to these perameters and the first time you drive aggresively it gets out of sinc. he said warm up the engine, tun it off unhook the ground wire from the battery then hold the brake pedal down for 20 seconds to discharge capacitors in ecu reconnect the ground wire and drive car for 20 minutes very aggressivilly. I did and it not only cleared the ;light and stayed off but there was huge increase in power. he recommended doing this every month

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