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96 Corolla: PO133 O2 Sensor


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rabbitrun
User

Mar 23, 2011, 6:20 AM

Post #1 of 9 (10748 views)
96 Corolla: PO133 O2 Sensor Sign In

1996 Toyota Corolla, 4 cyl, 1.8 L, 132,500 mileage:
• Started up car last night & malfunction indicator light (ie check engine light) came on.
Gas cap on snug (whooshing sound when removed); coolant full; oil & filter change done every 3k (last one 2460 miles ago); no evidence of oil leaks; probably burning oil as it was low a quart of oil
• Corolla had more than normal engine vibration 2 days ago; do not see same vibration now; repairman said extra vibration could have been caused when O2 sensor started acting up
• Free OBD diagnosis at parts store today was P0133 (Pre-converter oxygen sensor circuit slow response fault, Bank 1, Sensor 1, under hood near exhaust manifold)
• Repairman told me it’s safe to drive around as long as check engine light is solid & not blinking (blinking indicates serious problem like engine misfire; & car must be stopped & towed)
• Understand this could be faulty O2 sensor ($90 aftermarket to $173 OEM if I replace it), frayed/broken wiring to sensor, exhaust leak, or other----how to test if pre-converter O2 sensor needs to be replaced? If buy aftermarket, need to know if this sensor is upstream rather than downstream, heated rather than unheated, & 2 wire rather than 4 wire?
• Would like to get more use out of the car since I spent a pile of money on 120k maintenance 4 months ago (timing belt, drive belts, spark plugs, water pump, engine oil seals; air filter; antifreeze, oil & filter changed, & brake system flushed) ----but need to know if it’s time to cut my losses & trade in for newer used car?
• Or would you recommend clearing the code (by pulling 15A EFI fuse under the hood or removing negative battery cable or clearing w/ scan tool), & just wait to see if the light comes back on before taking it into the shop?
• Or would you recommend taking to shop to run diagnostic alone at $105 (1 hr labor to pull code, check how sensor is behaving, check for exhaust leaks, etc.); or pay $305 to run diagnostic & replace O2 sensor if that’s the problem?


zmame
Veteran / Moderator
zmame profile image

Mar 23, 2011, 4:33 PM

Post #2 of 9 (10729 views)
Re: 96 Corolla: PO133 O2 Sensor Sign In

Oxygen sensors only have certain life span.. When they get worn out they tend not to respond as fast as they did new.. If that's the only code then I would replace the O2. It would be nice to get on a scanner so you could monitor the switching to confirm %100 that this is your issue.


rabbitrun
User

Mar 24, 2011, 9:02 AM

Post #3 of 9 (10720 views)
Re: 96 Corolla: PO133 O2 Sensor Sign In

re: 96 Toyota Corolla DX 4 door 7AFE motor w/ 132,700 miles; 120k maintenance done 4 months ago & 13,720 miles ago:

thank you zmame. so if i buy an aftermarket O2 sensor for $100, what if it's something else like frayed/broken wiring to sensor, exhaust leak, or other?

if i buy aftermarket O2 sensor, aftermarket parts shop said i need to know if sensor is upstream rather than downstream, heated rather than unheated, & 2 or 4 wire? can you help with answers to these questions? toyota parts shop did not know answers to these questions for oem O2 sensor. p0133 in Haynes Manual shows code is pre-converter O2 sensor curicuit slow response fault---does that mean it is upstream? i saw the sensor near the exhaust manifold under the hood.

thanks!


zmame
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zmame profile image

Mar 24, 2011, 9:42 AM

Post #4 of 9 (10715 views)
Re: 96 Corolla: PO133 O2 Sensor Sign In

I doubt its frayed wire it would throw a different code. It would be heated sensor and it will be the upstream O2 (befor the converter).. just look and see how many wires are coming out of the O2. should be 4 if it's heated.1


rabbitrun
User

Mar 24, 2011, 10:35 AM

Post #5 of 9 (10713 views)
Re: 96 Corolla: PO133 O2 Sensor Sign In

zmame, w/ engine on, I crawled along both sides of car from front to end of muffler looking for any smoke & didnt see any except from the muffler tail pipe----how is an exhaust leak checked out?

if there were also problems with the O2 sensor down by the catalytic converter---would it show a separate code on the OBD tester?

pulled off electrical tape & see there are 2 wires. the plastic casing on the white wire is cracked in 1 spot like it got knicked in the past. would it make sense to pull out 15A EFI fuse & see if check engine light comes right back on before a mechanic looks at it (if i take it to a mechanic)?


so if it's 2 wire pre-converter OBD P0133 code, then i need an aftermarket O2 sensor that is 2 wire, unheated, upstream?


(This post was edited by rabbitrun on Mar 24, 2011, 11:27 AM)


rabbitrun
User

Mar 24, 2011, 10:59 AM

Post #6 of 9 (10710 views)
Re: 96 Corolla: PO133 O2 Sensor Sign In

 


(This post was edited by rabbitrun on Mar 24, 2011, 11:28 AM)


zmame
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zmame profile image

Mar 24, 2011, 2:43 PM

Post #7 of 9 (10696 views)
Re: 96 Corolla: PO133 O2 Sensor Sign In

You will need a 2 wire heated O2 sensor upstream.. A un-heated only has 1 wire coming from O2.. If there is a problem with down stream O2 it will set a separate code.. the rear O2 (downstream) dosen't switch all it does is make sure the converter is working properly. You don't need to pull the EFI fuse since its not even related to the O2 sensors.. I would replace the upstream O2 if you fell comfortable doing so.

Exhaust leaks are checked by someone holding rags on tail pipe at idle while you listen and look for leaks.. Black trail of soot is often a indication of a leak. there will be small holes in your resonator and or muffler so they can drain. a exhaust leak between the manifold and cat is the only thing that would affect upstream O2 reading.


(This post was edited by zmame on Mar 24, 2011, 2:48 PM)


rabbitrun
User

Mar 24, 2011, 8:26 PM

Post #8 of 9 (10690 views)
Re: 96 Corolla: PO133 O2 Sensor Sign In

re:1996 Toyota Corolla, 4 cyl, 1.8 L, 7AFE motor, 132,500 mileage:

zmame: today while driving on the freeway & then a side road 14 miles into the trip the check engine light went off & stayed off. i stopped by auto shop who checked it w/ obd scanner & even though the light has stayed off, it still read P0133 trouble code. with engine light going off & staying off but still reading code would you still change out O2 sensor?

preconverter O2 sensor is 2 wire so wouldn't it be an unheated, upstream 2 wire O2 converter?

the parts shop (not toyota dealership parts) has O2 sensor that is OE & another that is a universal----should I stick with the non Toyota parts shop OE ($90 for OE style) O2 sensor or is this something that i need to get from the toyota parts shop ($173 for OEM)?

i mentioned pulling the 15a EFI fuse only cause Haynes manual tells me that's best way to clear the codes.

if a rag is stuffed in the tailpipe, will it show an exhaust leak between the manifold and catalyst, or only a leak from the cat to the tailpipe?


thanks!


zmame
Veteran / Moderator
zmame profile image

Mar 25, 2011, 4:32 AM

Post #9 of 9 (10679 views)
Re: 96 Corolla: PO133 O2 Sensor Sign In

It is heated.. Go with OE, not universal.. Yes it would basically your adding pressure to the whole system.. if there was any amount of leakage that would cause bad reading you would notice it. The light will probably go on and off until it's replaced.. The computer will hold history codes or pending codes until it acts up again.






 
 
 






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