Smog

Hi, My car is due for renewal /smog( April) so I per checked at the station and I was told my catalytic converter is out and they could not till me what side I need to replace .Is their away to find out which cat I need to change or just replace both . I have been looking for used set I can buy , put no luck finding any in the parts market . If any one out their have set for sale let know . My car is 2002 C2. Thanks

i would think any professional scan tool that can look at the data from the oxygen sensors. i would also say if one was not working you would have a CEL

Quotes source post: 14004107

what was done when "checked at the station"? Did you go in for the smog renewal and you failed?

My choice would be to change both (if necessary to change one at all). So you've got a smog check guy saying something....now would be time to go to your shop of choice and actually investigate the issue and its source. I'd rather buy good quality new after market cats than used factory ones.

ex-tanker is correct. This is basic OBD2 work on a cheap scanner.The 02 sensors are easy to replace.See Pelican for diy & diagnostics. But I sense you may be apprehensive about doing this work ? Perhaps ask for a competent, honest Indie near Merced ? This is a task that any competent mechanic could do.JHM Audi in Stockton or perhaps someone in Fresno??

I do have Durametric tool,but I don't know what to look for while I am checking the O2 sensors. I don't have CEL at all . It dose show CAT fail on diagnostic for emission.

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First thing to do. Fire up Durametric and perform the "short test all modules" and see what codes you get under the DME. Under DME, there should be a way to display the current emission tests result (passed/failed) for o2 sensor, cats, evaps, etc. Note 'Failed" means "not ready". Check under "Ready Status".

This may help -Start here: http://www.durametric.com/troublesho...rsche-9x6.aspx see page 12 here : http://www.durametric.com/Durametric...ion_Manual.pdf Check some actual values. Check for codes.. It is a steep learning curve as I am discovering also !

If your catalytic converter has been contaminated by oil ,there are diy ways of trying to remedy the problem. The more data you can give from Durametric the better. Can you copy and post the Freeze Frame data for us? O2 sensor codes are infamously 'spurious'. Try cleaning the MAF. Use the Pelican diy.It is fragile.

Durametric readings would be a great place to start. From reading others woes on passing smog check, you need to make sure your cats are hot. A good 30 mile highway run prior to checking the cats is what worked for some.

I did the short test and I had no codes at all did the emission test and shows CC fail

Has the battery been disconnected or there's a power loss recently? If one of your cats is bad, you will get at least a pending code. As mentioned before "Fail" here could mean the test just has not been performed.

Would it also "Fail"if the engine was not completely warmed up when the test was made perhaps?

I had code While back like three weeks ago and I reset CEL ( P01492). Since then I put around 150 miles. The battery has not been disconnected. I did this read out after I had drove the car today for 15 miles so it was at operational temp.

It's likely you need to drive the car more. Either that test will Pass or you will get some codes. If you want to actively monitor the cats, drive the car to warm up the engine fully then let it idle. Use Durametric to read the O2 sensor voltage (both precat and postcat). The precat should swing between 0.2 to 0.7v every second. The postcat should stay more or less at 0.7v steady. If the post cat voltage mimics the precat on the same bank, the cat is bad. Btw, P01492 is not a valid error code.

I meant P0492, here pic of the voltage on the O2 .

Bank 1 O2 voltage

You need to monitor the voltage for 30s or so to see the pattern, then repeat for bank 2. P0492 is insufficient air injected to bank 2 so it has nothing to do with the cats. ​​​​​​Your secondary injection is PASS so the SAI system is ok for now.

I'll will do that first thing tomorrow , thanks for all the help Ahsai .

You're welcome! If you manage to log the O2 sensor voltage (all 4 of the sensors) during cold start, you can see how well your SAI system performs. See post #6 here https://rennlist.com/forums/996-foru...l#post11746570 This is not your current concern though. To diagnose the cats, just make sure your engine is fully warmed up before taking reading with Durametric. The precat O2 sensor should swing between 0.2v to 0.7v every few seconds. I know I said every second in my previous post but that depends. The point is the precat sensors should keep swinging periodically and the postcat sensors should stay at ~0.7v steady.

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This used to be the case but in CA (where the OP is), the smog is just reading OBDII readiness now and it takes only 5 minutes. As long as all the readiness flags are set, you will pass (barring any visual violations). OP, as long as Durametric "Ready Status" shows "PASSED" in all tests, you should be good to go for the smog test.

The data needed for the test is not sufficient to test for the CC. If your looking to reset the Readiness Monitors this is the work sheet that I came up with from searching the net last year: Start engine, idle cold for approx. 2 min, 10 secs. Accelerate to 20-30 MPH, Maintain steady speed for approx 3 min, 15 secs. Accelerate to 40-60 MPH, Maintain steady speed for approx 15 mins. Decelerate and come to a stop. Idle in gear* for approx 5 mins. 1..As soon as the engine starts, idle the engine in drive for two and a half minutes with the A/C and rear defrost on. OBDII checks oxygen sensor heater circuits, air pump andEVAP purge. 2. Turn the A/C and rear defrost off, and accelerate to 55 mph at half throttle. OBDII checks for ignition misfire, fuel trim and canister purge. 3. Hold at a steady state speed of 55 mph for three minutes. OBDII monitors EGR, air pump, O2 sensors and canister purge. 4. Decelerate (coast down) to 20 mph without braking or depressing the clutch. OBDII checks EGR and purge functions. 5. Accelerate back to 55 to 60 mph at half throttle. OBDII checks misfire, fuel trim and purge again. 6. Hold at a steady speed of 55 to 60 mph for five minutes. OBDII monitors catalytic converter efficiency, misfire, EGR, fuel trim, oxygen sensors and purge functions. 7. Decelerate (coast down) to a stop without braking. OBDII makes a final check of EGR and canister purge. just hold the following RPM ranges from 2-5 minutes: Idle 1500 2000 2500 3000 Idle the checks usually happen before the 5 minutes is up, but without a scan tool hooked up you won't know when it happens.

There you have it folks - a Durametric(or similar) test (no dirty hands required!) that could save you a small fortune on a replacement catalytic converter replacement job ! Look at these prices then imagine you replaced the Cat but still got the code because you did not know about MVP Ahsai's Durametric test. : http://www.pelicanparts.com/catalog/...EXHMUF_pg1.htm A back pressure test would show if the Cat is 'plugged' Here is a link showing what the Test Ahsai mentioned looks like on the screen: https://www.discountconverter.com/te...rter-&News=218 Ahsai said: "I t's likely you need to drive the car more. Either that test will Pass or you will get some codes. If you want to actively monitor the cats, drive the car to warm up the engine fully then let it idle. Use Durametric to read the O2 sensor voltage (both precat and postcat). T he precat should swing between 0.2 to 0.7v every second. The postcat should stay more or less at 0.7v steady . If the post cat voltage mimics the precat on the same bank, the cat is bad. Btw, P01492 is not a valid error code . "

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I have to laugh, where exactly anywhere other than on a track would you be able to do that exact sequence?

There are simpler versions that have come up here recently . Search "Drive Cycle" , "Readiness"

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You can do it out of sequence - each step sets the appropriate monitor to "ready". I've done it both ways although in sequence required me to map out a pretty specific course and do it very early in the morning.

I just had this happen on my cats as well. This is what worked for me: Let car warm up 3mins Do not go over 3k rpms (during this drive cycle) Drive to nearest freeway (helps if it's really early in the am) Stay in the slow lane and be prepared to get passed by semi's Set cruise control for 59mph under 3k rpm Drive for about 15 to 20 mins at this speed exit the freeway slowly check your sensors Either you'll throw a code or the cat sensor will pass.

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Thank you - that is really helpful.

Ok here is the pre cat voltage reading on both O2 and after while the car up to opperational temp . Thanks for all the help.

If the pattern alternates between your 1st and 2nd screenshot and the last screenshot remains the same, your cats may be ok. Just drive it more and see.

Yes it alternates the voltage readout every second or two, going to give "Drive Cycle Readiness" a shot. Thanks for all the responds and all inputs .

some times if you disconnect the battery or have it run low you will have to go through this all over again.

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You missed my recent smog thread? Same issue.... had a fail for cat sensor not ready. Took me three tries to do the sequence. Finally got it when I went out to Old Hwy 395 in Bonsall.

Great news and $$$ saved by following all the al the feed back from you guys many thanks , I did the drive cycle and it worked on the first try .

Which drive cycle did you use? The long one or the short one in Post #27 above?

I did the short one post #27 .

I did the cold start voltage read out on the O2's as Ahsai asked for. I did the cold start voltage read out as Ahsai asked for too.

Excellent and congrats! Your SAI looks OK to me at this time.

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Glad it worked for you too!

Human911 thanks for posting your drive cycle. It worked berfictly on the first try , I passed smog test today.

Congrats! BTW, do you remember what's your gas level when you performed the drive cycle? Was it between 1/2 and FULL?

It was 3/4 of tank . and I drove the car 57 mph 2100 rpm for 11 miles only to have it pass .

Since the CEL popped before for converter inefficiency and it then passed the readiness test. That converter is marginally passable at the moment and it will only get worse over time. So be prepared to have to address this probably before your next emission test.

Had the same issue this morning at the smog station . Did the short drive cycle and returned to the station. Car passed with no problems . Thanks for the tips guys. As an added note gas tank was at 1/2 Alan

Excellent info. The reason i asked about the tank level was because one poster (a retired tech?) mentioned some of those tests require the tank to be between 1/2 to 3/4 as a pre-condition to trigger the tests.

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Glad to hear

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The 1/3 - 2/3 tank is only needed for the Evap system testing. The converter efficiency and O2 sensor checks happen regardless of the fuel level in the tank. Evap system readiness takes the longest too and usually is the last system to be completed.

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Yes, that's the way I understand it because the fuel level should not affect the cats test (while it will definitely affect the evap tests). I just want to make sure that is truly the case.