CEL P0135, fixed, and now P0420

[Mark]

I have a '97 ES300 with 112K miles. I had got a CEL with P0135 code. I
replaced the bank 1 sensor 1 O2 sensor with a OEM sensor. Two days
later, I get another CEL and now the code is P0420 - catalyst
efficiency below threshold.

I had the P0420 code about 6 months ago and I had replaced the cat.
Since then P0420 code was gone and everything was fine.

Any ideas why I am getting P0420 now, after P0135 and after I replaced
the O2 sensor? What should I be replacing now?

Thanks,
Mark

[Ray O]

Post by Mark
I have a '97 ES300 with 112K miles. I had got a CEL with P0135 code. I
replaced the bank 1 sensor 1 O2 sensor with a OEM sensor. Two days
later, I get another CEL and now the code is P0420 - catalyst
efficiency below threshold.
I had the P0420 code about 6 months ago and I had replaced the cat.
Since then P0420 code was gone and everything was fine.
Any ideas why I am getting P0420 now, after P0135 and after I replaced
the O2 sensor? What should I be replacing now?
Thanks,
Mark

You should not be replacing anything until you check the Bank 1 Sensor 1,
Bank 2 Sensor 1,and Bank 1 Sensor 2 output. Check voltage fluctuation and
frequency of voltage fluctuation.

When you replaced the cat, did you use an OEM or an aftermarket cat?

[Mark]

On Sep 26, 11:19 pm, "Ray O" <rokigawaATtristarassociatesDOTcom>

Post by Ray O

Post by Mark
I have a '97 ES300 with 112K miles. I had got a CEL with P0135 code. I
replaced the bank 1 sensor 1 O2 sensor with a OEM sensor. Two days
later, I get another CEL and now the code is P0420 - catalyst
efficiency below threshold.
I had the P0420 code about 6 months ago and I had replaced the cat.
Since then P0420 code was gone and everything was fine.
Any ideas why I am getting P0420 now, after P0135 and after I replaced
the O2 sensor? What should I be replacing now?
Thanks,
Mark

You should not be replacing anything until you check the Bank 1 Sensor 1,
Bank 2 Sensor 1,and  Bank 1 Sensor 2 output.  Check voltage fluctuation and
frequency of voltage fluctuation.
When you replaced the cat, did you use an OEM or an aftermarket cat?
--
Ray O
(correct punctuation to reply)

There is a long history to my cat replacement, which was discussed in
this thread here: http://groups.google.com/group/rec.autos.tech/browse_thread/thread/99a4e98aff0cf8a9

The summary of that issue was, I initially replaced it with a crappy
aftermarket cat. It was fine for ~6 weeks until I had got a fuel
injection service. A couple of weeks after that I got the P0420. There
was discussion on whether it was the cat that was bad, or the fuel
injection service damaged it, or both.

Ultimately, I took it to my trusted mechanic, (the guy who put the
crappy cat was a local guy, not my trusted mechanic) who replaced it
with a superior quality cat. If I recall, it was either an oem for
another car model or just superior in quality. Since then, I didn't
have any issues with that cat.

[Ray O]

"Mark" <***@hotmail.com> wrote in message news:b594eebe-93e7-4f01-b06e-***@j22g2000hsf.googlegroups.com...
On Sep 26, 11:19 pm, "Ray O" <rokigawaATtristarassociatesDOTcom>

Post by Ray O

Post by Mark
I have a '97 ES300 with 112K miles. I had got a CEL with P0135 code. I
replaced the bank 1 sensor 1 O2 sensor with a OEM sensor. Two days
later, I get another CEL and now the code is P0420 - catalyst
efficiency below threshold.
I had the P0420 code about 6 months ago and I had replaced the cat.
Since then P0420 code was gone and everything was fine.
Any ideas why I am getting P0420 now, after P0135 and after I replaced
the O2 sensor? What should I be replacing now?
Thanks,
Mark

You should not be replacing anything until you check the Bank 1 Sensor 1,
Bank 2 Sensor 1,and Bank 1 Sensor 2 output. Check voltage fluctuation and
frequency of voltage fluctuation.
When you replaced the cat, did you use an OEM or an aftermarket cat?
--
Ray O
(correct punctuation to reply)

There is a long history to my cat replacement, which was discussed in
this thread here:
http://groups.google.com/group/rec.autos.tech/browse_thread/thread/99a4e98aff0cf8a9

The summary of that issue was, I initially replaced it with a crappy
aftermarket cat. It was fine for ~6 weeks until I had got a fuel
injection service. A couple of weeks after that I got the P0420. There
was discussion on whether it was the cat that was bad, or the fuel
injection service damaged it, or both.

Ultimately, I took it to my trusted mechanic, (the guy who put the
crappy cat was a local guy, not my trusted mechanic) who replaced it
with a superior quality cat. If I recall, it was either an oem for
another car model or just superior in quality. Since then, I didn't
have any issues with that cat.
***************

Looking through that thread, there is a mix of good and bad information and
advice.

Aftermarket cats are a hit-or-miss proposition, and I've read and heard of
more people with bad luck than good luck with them. As expensive as OEM
cats are, IMO, they are the only way to go.

At this point, check the O2 sensors as I mentioned above. If the Bank 1
Sensor 2 checks out, then the cat isn't working properly.

[j***@hotmail.com]

With a P0420 you should never rush out to replace the converter. The
problematic Denso thimble type oxygen sensors are more frequently the
culprit in these cases.

Field diagnosis of oxygen sensors are difficult and may not be
accurate (eg, sensor bad but no codes). So if you the engine is
properly tuned, no vacuum/exhaust leaks, then consider replacing the
downstream sensor with a Bosch *PLANAR* type sensor more resistant to
contamination, not the *THIMBLE* type junk.

http://www.boschautoparts.com/Products/OxygenSensors/PlanarO2.htm

Loading Image...
BOSCH Part # 13353 4 Wire; Planar Downstream $78.79

Post by Mark
I have a '97 ES300 with 112K miles. I had got a CEL with P0135 code. I
replaced the bank 1 sensor 1 O2 sensor with a OEM sensor. Two days
later, I get another CEL and now the code is P0420 - catalyst
efficiency below threshold.
I had the P0420 code about 6 months ago and I had replaced the cat.
Since then P0420 code was gone and everything was fine.
Any ideas why I am getting P0420 now, after P0135 and after I replaced
the O2 sensor? What should I be replacing now?
Thanks,
Mark

[Mark]

Post by j***@hotmail.com
With a P0420 you should never rush out to replace the converter. The
problematic Denso thimble type oxygen sensors are more frequently the
culprit in these cases.
Field diagnosis of oxygen sensors are difficult and may not be
accurate (eg, sensor bad but no codes). So if you the engine is
properly tuned, no vacuum/exhaust leaks, then consider replacing the
downstream sensor with a Bosch *PLANAR* type sensor more resistant to
contamination, not the *THIMBLE* type junk.

Since I just replaced the bank 1 sensor 1 with the OEM sensor, I
suppose it would be okay to "mix and match", and replace the
downstream sensor with this bosch one? After my cat experience, I'm
just too skeptical to use non-oem parts for emission components, so
pardon me if my questions sounds silly.

Thank you.

[Ray O]

Post by j***@hotmail.com
With a P0420 you should never rush out to replace the converter. The
problematic Denso thimble type oxygen sensors are more frequently the
culprit in these cases.
Field diagnosis of oxygen sensors are difficult and may not be
accurate (eg, sensor bad but no codes). So if you the engine is
properly tuned, no vacuum/exhaust leaks, then consider replacing the
downstream sensor with a Bosch *PLANAR* type sensor more resistant to
contamination, not the *THIMBLE* type junk.

Since I just replaced the bank 1 sensor 1 with the OEM sensor, I
suppose it would be okay to "mix and match", and replace the
downstream sensor with this bosch one? After my cat experience, I'm
just too skeptical to use non-oem parts for emission components, so
pardon me if my questions sounds silly.

Thank you.
************
It is OK to mix OEM and aftermarket parts, but before you go and replace any
sensors, check their function. I suspect that B1S1 (Bank 1 Sensor 1), B2S1,
and B1S2 are all OK because the nature of P0420 means that B1S2 sees a
signal that matches B1S1 instead of a more steady signal that would result
if the cat was working. If the sensors are good and the cat is bad, you
would probably end up with the same trouble code.

Checking the sensor output voltages and frequencies would eliminate them as
the cause and point to a bad catalytic converter. If you don't want to
bother checking the sensors and prefer to just replace parts in hopes of
solving the problem, replace the aftermarket cat with an OEM one. Of
course, an OEM cat is fairly expensive, so spending 10 or 15 minutes to
check the sensors is probably worth the time.

[01dyna]

On Sat, 27 Sep 2008 17:19:56 -0500, "Ray O"

Post by Ray O
Checking the sensor output voltages and frequencies would eliminate them as
the cause and point to a bad catalytic converter. If you don't want to
bother checking the sensors and prefer to just replace parts in hopes of
solving the problem, replace the aftermarket cat with an OEM one. Of
course, an OEM cat is fairly expensive, so spending 10 or 15 minutes to
check the sensors is probably worth the time.

hey Ray,

this is probably a dumb question, but isn't the emission system,
specifically the cat system, supposed to be covered by the
manufacturers warranty for something like 100k miles?

[Ray O]

Post by 01dyna
On Sat, 27 Sep 2008 17:19:56 -0500, "Ray O"

Post by Ray O
Checking the sensor output voltages and frequencies would eliminate them as
the cause and point to a bad catalytic converter. If you don't want to
bother checking the sensors and prefer to just replace parts in hopes of
solving the problem, replace the aftermarket cat with an OEM one. Of
course, an OEM cat is fairly expensive, so spending 10 or 15 minutes to
check the sensors is probably worth the time.

hey Ray,
this is probably a dumb question, but isn't the emission system,
specifically the cat system, supposed to be covered by the
manufacturers warranty for something like 100k miles?

I don't consider any questions dumb the first time they're asked. The
catalytic converter and O2 sensors would be covered by the 8 year, 80,000
mile federal design and defect warranty, but the OP's 97 ES with 112,000
miles is outside of warranty coverage by time and mileage.

[Mark]

I took the car to my mechanic to have him check the other two O2
sensors. He asked me to buy 'catalytic converter cleaner' and put it
in the gas tank. That should clean the cat and the CEL should go away.
Anybody have any prior experience with this cat cleaner? Does it work?
Does it do any harm? I wouldn't mind trying it as long as it does not
cause more damage.

[Ray O]

Post by Mark
I took the car to my mechanic to have him check the other two O2
sensors. He asked me to buy 'catalytic converter cleaner' and put it
in the gas tank. That should clean the cat and the CEL should go away.
Anybody have any prior experience with this cat cleaner? Does it work?
Does it do any harm? I wouldn't mind trying it as long as it does not
cause more damage.

I doubt if the catalytic converter cleaner will work, but it probably
wouldn't hurt to try it.