QuestionThanks Dinger,
Interesting that use mentioned the fuel injectors. Two weeks prior to the check engine light comming on we had the car into the dealer and and they had this to say about the work they did:
Vehicle MIL light is on. Test and inspected. Verified MIL lamp, EEC system tests codes P0401, EGR insufficient flow, chamber plugged and DPFE sensor failed. Replace sensor and clean EGR ports. Add 44 BG additive, retest all OK at this time.
Does this new information say anything to if it could be the cause of the latest problem. Could the converters actually be OK? The dealer explained the testing process they used (sensor for inflow to converter - sensor for outflow from converter) to determine it was actually the converters. Could the condition resolve itself? Might a second opinion be worthwhile?
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Followup To
Question -
Timeline:
Check engine light comes on.
Two weeks later fail emissions test with P0420 & P0430. (confirm codes using Schucks scanner).
Two days later dealer diagnoses both catalytic converters need replacement and says needed to jump car to start it that morning. (Had suspected battery was on last legs.) Car started for me that afternoon when I picked it up (Didn't have the dealer fix anything.) Cleaned battery posts and terminals that night.
Next day replace battery (as was only getting a chatter out of the start). Check engine light is no longer on and fault codes no longer show up in OBD scan (using Schucks scanner).
Drive car 600 miles over next day and a half.
Pass emissions re-test and go to dealer to inquire about turn of events (didn't tell dealer had passed emission test).
Dealer says car's computer is learning one and replacing the battery would have cleared out the P0420 & P0430 codes however this would have placed a P1000 code in their place which would have caused emission test to fail (this obviously wasn't the case).
Check engine light came back on two days after conversation with dealer and suspect the P0420 & P0430 codes are back (haven't confirmed yet).
Would appreciate any feedback on reasonable this series of events seems. Curious about why P1000 never occurred. Should I be able to find after market converters as they are built into the exhaust manifolds? How immediately should I replace the converters? Thanks.
Answer -
Hi Kevin,
P1000 is that the car hasn't been run enough to learn, or reset this code. It only takes a few miles to do this, hence you passed smog, because the P1000 had cleared because the vehicle was driven enough to cycle. Also, yes, removing the battery cleared the other codes. As for P0420 and 430, these indicate that there is a deterioration of the internal parts of the catalytic converters. However, this can code can be set be abnormal engine operation before the cat. Vacuum leaks and misfires, just to name a couple. These cause the cats to overheat and pops that code. If you have used an additive to clean your fuel injectors it could cause the cat to clog. They mention leaded fuel also.
D1.) Catalyst Efficiency Monitor - Information
The Federal Test Procedure Catalyst Monitor monitors for deterioration in the catalyst system and illuminates the MIL when tailpipe emissions exceed the appropriate HC emission thresholds. The Catalyst Monitor is enabled after the upstream and downstream HO2S sensors have been tested and verified to be functional. This monitor relies on the front and rear heated oxygen sensors (HO2S) to infer catalyst efficiency based upon oxygen storage capacity. Under normal closed loop fuel conditions, high efficiency catalysts have oxygen storage which makes the switching frequency of the rear HO2S quite slow compared with the frequency of the front HO2S. As catalyst efficiency deteriorates, its ability to store oxygen declines, and the rear HO2S begins to switch more rapidly, approaching the frequency of the front sensor. In general, as catalyst efficiency decreases, the switch ratio increases from a switch ratio of 0 for a low mileage catalyst to a switch ratio of 0.8 or 0.9 for a low efficiency catalyst.
Some vehicles will monitor substantially less than the entire catalyst volume in order to meet the stringent catalyst monitoring malfunction thresholds. In many cases, only the front, light-off catalyst is monitored.
Front and rear HO2S switches are counted under specified closed loop fuel conditions. After the required number of front switches are obtained, a rear-to-front HO2S switch ratio is calculated. The switch ratio is compared against a threshold value. If the switch ratio is greater than the calibrated maximum limit, the catalyst has failed. The test entry conditions for the Catalyst Efficiency Monitor are as follows: ECT or CHT (warmed engine), IAT (not at extreme ambient temperatures), MAF (greater than minimum engine load), VSS (within vehicle speed window) and TP (at part throttle) are required.
^ Because an exponentially weighted moving average is used for malfunction determination, up to six OBD II drive cycles may be required to illuminate the MIL.
NOTE THE CATALYST MONITOR ON SOME EARLY OBD II VEHICLES (SOME 1994-1996 VEHICLES) WAS REFERRED TO AS THE "STEADY-STATE CATALYST MONITOR" AS OPPOSED TO THE "FTP CATALYST MONITOR" (DESCRIBED ABOVE) THAT IS MOST COMMON FOR VEHICLES BUILT AFTER 1996. BELOW IS A BRIEF DESCRIPTION OF THE STEADY-STATE CATALYST MONITOR:
The Steady-State Catalyst Monitor performs a 20 second test during steady state rpm and load conditions. The Monitor transfers closed loop fuel control from the front to the rear 02 sensors. The Monitor then observes the switching frequency and compares it to a threshold frequency stored in an rpm/load table. A frequency higher than the maximum calibrated threshold indicates a malfunction.
The Catalyst Monitor DTCs can be categorized as follows:
^ Catalyst system efficiency below threshold (Bank
1) - P0420
^ Catalyst system efficiency below threshold (Bank
2) - P0430
Other casues of this code are cylinder head temp sensor, high fuel pressure, damaged exhaust manifold, Downstream HO2 Sensor wiring issues, bad muffler and tailpipe, retarded spark timing.
Damaged Converter can be caused by but not limited to leaded fuel, exessive oil consumption and silicone sealents and cleaners.
Now you know the rest of the story!
AnswerWell, anything is possible, I don't know what kind of service you have done over the years, but that 3 page sheet I sent you is about all I have on this. I could see if it was one, but having both go is one of two things. Yes, they are both bad, or the is a possible vacuum leak. Or any of the items I listed in my previous answer.
