elantra 2001 has no oxygen sensor and it ECU runs in open loop always!

Hi all, I recently bought an Elantra 2001 model car. When i did the emmission test, it failed with high CO and HC. CO percentage was in range 5-6. Its fuel consumption is also very high.
The idle is very smooth, no knocking when accelerating and no other unusual behavior either.
As the first thing, i replaced all spark plugs, got the distributor checked and wires checked. They are all fine. Then i did a fuel system clean and checked whether there are any problems with injectors and they were fine too.
Today, i got its ECU scanned and it gave the code p0342. I replaced the camshaft position sensor, but it still gives the same code. In addition, the reading of oxygen sensor voltage is 0.0V always. When inspected, we could not find any oxygen sensor! And the engine runs always in open loop (even after it gets heated!). Now im fully confused! Please let me know whether there are engines where you don't have a oxygen sensor? And if there are engines like that, will they run in open loop always?
thanks in advance!
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You'll find the front oxygen sensor in the exhaust manifold-- it screws into the transmission side of the manifold. The rear oxygen sensor is in the front exhaust pipe. If you actually had no oxygen sensor, you'd have trouble codes indicating an open heater circuit for each sensor. I'll note, however, that since closed loop by definition uses front oxygen sensor values to determine how much fuel to deliver, lack of oxygen sensors would mean the vehicle would always operate in open loop.
With the recurring P0342, you should check the camshaft timing. It's possible that it's one tooth off. This would cause the emission failure and the odd oxygen sensor readings.
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Thanks for the valuable advice, i will check for timing. BTW, i got the shop manual for the car and according to it, this car was made for leaded petrol and has no oxygen sensors or catalytic converters. As you have mentioned, this should run in open loop always, i believe. And one more help, Would a wear and tear of petrol injectors increase the CO emission to 4%. The mileage of the car is 167000 KM.
thanks
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Suppose I shouldn't have assumed. This car isn't in the U.S., is it?
An injector issue would typically cause the car to run poorly, so that isn't likely the issue. Stick with sorting out the reason for the cam sensor code. Fixing that will likely fix the emissions.
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thanks. the car was made for Sri Lanka. Is there a place where i can but the correct manual for this car by giving the VIN? i checked the local agent and they say they dont sell it to customers. (so that they can have the service monopoly !)
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I'm not knowledgeable enough about non-US cars to know where that would be. You can register for an account at www.hmaservice.com, but it includes information only for U.S. models. At this point, I don't know if your engine is the same as one of those available in the U.S.
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