93 Camry failed smog - O2 sensors
 

Hi,

My 93 Camry v6 failed smog (california) twice. I replaced the Catalyst Converter after the 1st failure but failed the 2nd time. I was told it could be the O2 sensors. I replaced both upstream sensors with the Denso Universal model #234-1057. If I have both sensors installed but disconnect the connector, the check engine light doesn't comes on. Is this normal? This is a single wire O2 sensor. How can I test to see if the wire connection is still good? Also, any information on why it failed smog is greatly appreciated. Btw, this car is from New Mexico so it doesn't have the downstream O2 sensor. It shouldn't be any problem passing california smog, right?

Here are my smog test results:

Test #1 - No replacement part, done at regular smog station
HC (PPM) CO (%) NO (PPM)
MAX AVE MEAS MAX AVE MEAS MAX
AVE MEAS
15 mph 84 27 174 0.49 0.02 0.57 692 147 1810
25 mph 34 16 35 0.46 0.03 0.07 711 134 228


Test #2: Replaced Catalyst converter done at smog only station

HC (PPM) CO (%) NO (PPM)
MAX AVE MEAS MAX AVE MEAS MAX
AVE MEAS
15 mph 84 270 181 0.49 1.99 0.59 692 1912 2814
25 mph 34 220 34 0.46 1.96 0.14 711 1712 398

Thank You

California appears to have a one-time waiver allowing a 2 year extension for passing the test if $450 was spent on repairs at a smog station. Check the states emissions website.

The check engine light comes on when the sensors are connected?

Is the check engine light on?

The emissions NO levels seem to have greatly increased after the converter was replaced, is this correct?

There should be a downstream sensor but these seldom fail.

Thanks for the waiver info..I'll look into this. I just purchased this used car but can't seem to get pass the smog. This car is from New Mexico so there isn't a down stream sensor. I looked and confirmed there isn't one after the CAT, just 2 upstream before the CAT.

The check engine never came on. I was told to replace the cat after the 1st failure and the 2nd test was done about 3-4 days later. I ran the car for about 1hr (so it's hot) before taking it in for the 2nd test. I also noticed everything for the 15mph gone up higher after changing the CAT. After the 2nd failed test, the smog technician thinks the O2 sensors are bad. Again, no check engine light, even after changing both upstream O2 sensors and left both unconnected. I would think the check engine light would come on. Could it be a faulty or bad ECU? My mechanic said the EGR checks out fine but I'm not certain. How can I check/test the EGR system, O2 wiring, and ECU are working properly? What are the emission components involve in passing smog beside the CAT, OS sensor, EGR? How long should I wait/drive the car after changing the CAT and O2 sensors for the ECU system to learn before taking it in for a retest. I haven't done so since replacing the sensors.

Btw, does anyone know where the ECU unit is located on this 93 v6 camry?
Any help would be much appreciated, and thanks in advance.

Did you look on top of the exhaust pipe for the sensor?

The cars diagnostic system must complete a test (most likely 2 times) and fail each time before a code will be set. The test requires certain MPH, time, etc. Perhaps the tests were never completed and the check light did not come on.

If no codes were set the computer should not be required to reset for the new parts.

ECU is behind glove box.

Are you going to a certified smog shop. They should have the emissions equipment to test the cars emissions at the shop and not guess.

In the past one could find a shop that would guarantee smog passage for a price. The state tried to crack down on this but never know may be able to still find one.

I did almost the same thing... it was couple of months ago...ask someone to do it and just paid him much $$$ and my Camry is working perfect now.

1) Did you look on top of the exhaust pipe for the sensor?
yes, my mechanic and I went under the car, checked the exhaust pipe from front to back and found no downstream sensor. He thinks it doesn't have one since it's no a California car.

2) The cars diagnostic system must complete a test (most likely 2 times) and fail each time before a code will be set. The test requires certain MPH, time, etc. Perhaps the tests were never completed and the check light did not come on.
Ok, didn't know this. I drove it one full day (to work and back about 50 miles) with both sensors disconnected but no CEL yet. Will continue driving it to see if it comes on.

4) If no codes were set the computer should not be required to reset for the new parts.
I disconnected the battery (both cables) for an hour and reconnected it to reset the ECU. I'm hoping this will help.

5) ECU is behind glove box.
Great. I'll look for it.

6) Are you going to a certified smog shop. They should have the emissions equipment to test the cars emissions at the shop and not guess.
Yes, 2 different ones. I have a free re-test but want to verify everything is working before taking it in for the 3rd test.

7) In the past one could find a shop that would guarantee smog passage for a price. The state tried to crack down on this but never know may be able to still find one.
I wish but I rather get it fix so the car runs more efficient and not pollute the air so much.

I'm hoping someone can guide me on how to verify the following components:

a) Check if the O2 sensor wire connection from the sensor to the ECU is good. The easy way is to check the wire continuity with a multi-meter but what's the best way since one end of the wire is on the engine and the other is under the glove box.
b) Check if the ECU is not faulty and working fine. I manage to trigger the CEL by disconnecting one of the temperature sensor. There are 2 above the engine (green and red), one triggers the CEL when disconnected but the other doesn't. Again, not sure why. Anyone knows what they are? I think one is the coolant sensor.
c) Check if the new OS sensors are recognized by the ECU. This is the reason why I disconnected the 2 O2 sensors connection to trigger the CEL, then reconnect them to see if it goes off. Any other way to test this.
d) Check if the EGR value is working properly. What/how can I clean it?

Thanks again for all that replied.

The smog failed for the 3rd time after changing both upstream O2 sensors, clean the EGR valve, hoses, air flow sensor, the temp & coolant sensors are still new. It looks like the replacement and cleaning wasn't the issue. We did notice steam with coming out of the exhaust pipe and some water dripping out. One of the customer waiting to smog his car thinks it may be a head gasket problem but the car runs great, no overheating, the temp gauge stays at 1/3 and never exceeded the half point mark. I notice the results went up after changing the CAT (test #2), not sure why. The different is test #1 was done at a regular smog station whereas the 2nd was done on a test only station. Are the tests the same on both type of stations? Any suggestion on what I should check for now?

Here are the smog results in better formatting:

Test #1 - No replacement part, test at regular smog station

15 mph (Fail)
HC (PPM) Max: 84, Ave: 27, Meas: 174
CO (%) Max: 0.49, Ave: 0.02, Meas: 0.57
NO (PPM) Max: 692, Ave: 147, Meas: 1810

25 mph (Fail)
HC (PPM) Max: 34, Ave: 16, Meas: 35
CO (%) Max: 0.46, Ave: 0.03, Meas: 0.07
NO (PPM) Max: 711, Ave: 134, Meas: 228

Test #2: Replaced Catalyst converter, retest at smog only station. the results went higher, not sure why.
15 mph (Fail)
HC (PPM) Max: 84, GP: 270, Meas: 181
CO (%) Max: 0.49, GP: 1.99, Meas: 0.59
NO (PPM) Max: 692, GP: 1912, Meas: 2814

25 mph (Pass)
HC (PPM) Max: 34, GP: 220, Meas: 34
CO (%) Max: 0.46, GP: 1.96, Meas: 0.14
NO (PPM) Max: 711, GP: 1712, Meas: 398

Test #3: Replaced both upstream sensors, clean EGR valves/hoses, and visual check the MAF, temp, coolant sensors, re-test at smog only station. the results went down a little.
15 mph (Fail)
HC (PPM) Max: 84, GP: 270, Meas: 162
CO (%) Max: 0.49, GP: 1.99, Meas: 0.55
NO (PPM) Max: 692, GP: 1912, Meas: 2155

25 mph (Pass)
HC (PPM) Max: 84, GP: 270, Meas: 34
CO (%) Max: 0.46, GP: 1.96, Meas: 0.28
NO (PPM) Max: 711, GP: 1712, Meas: 398

Thank You

Did you look into getting a waver based on all the $$ spent? A waver will give you time to work on the issue and not be under pressure to pass the test.

Post a private message with your email address. We send some files for checking the EGR and O2 sensors.

There is a sticker under the hood which states if the car was built to FED or CA emissions standards. Does the engine have a converter shaped like a large can mounted on the cylinder exhaust manifold as in right after the exhaust comes out of the head?

The one number listed for test #3 as 28155 is this correct?

In the listing of emissions what does GP stand for?

Does the engine burn a lot of oil?

A blown head gasket will show up by needing to add coolant to the over flow tank. If the tank level is staying the same over time (and not coolant system leaks), the gasket should be OK.

Anyone do a compression check?

Hey Toyomoto - just sent you a private message w/ my personal email.

The california smog waiver/extension only applies to a vehicle that is currently registered in California and had already been passed smog. Unfortunately, this car is registered in New Mexico so I'm out of luck, not even qualify for any smog repair assistance or retirement programs.

You brought up a good question about the type of emission for this car. Since it's a non-California car, I assumed it was built for FED emission standard. If a California type CAT converter was installed they replaced the old one, would this contribute to the smog failure? I also smell oil burn but much dripping down the ground. Where would an oil leak occurs? What should I check for?

A typo on test #3 result, it should be 2155 instead of 28155. I'm not sure what the GP, it's from the test only station smog result.

The sticker under the hood labeled as "62180 3VZ-FE FED & CANADA" CATALYST. It looks like it was built to Federal and not California standards but the replacement CAT is since I had it changed. Could this be the problem all along? Can a car built to Federal standard be made to pass California smog standards? Since this car never passes or registers in California, I'm not eligible for the 2 yr smogs waiver, repair assistance, or the retirement option. Any helpful information on how to get this car passes smog (if it's possible) will be greatly appreciated.

Btw, is the catalyst converter what made the car compliant with the Federal or California standards? or are there other components in the emission system involved?