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97 Camry throwing P0420 and P1210

6K views 9 replies 3 participants last post by  mcgowaw 
#1 ·
Hey guys,

My Camry is giving me a little headache and I was wondering if you could help. The engine light came on, when I was driving on a hot summer day and felt like I need to turn the AC on. Same thing actually happen last year, but at this point I deleted the codes and didn't bother investigating as long as the light wouldn't show up again. But in general I feel like the engine lacks of power, especially with the AC on or when it's very humid outside. I feel like in the summer and the winter it's better. But sometimes I feel like I'm hitting the gas pedal and nothing is happening.

Anyway... engine light came on and I got following readings:
P0420: Catalyst System Efficiency Below Threshold Bank 1
P1210: No DTC definition found

Now regarding the P1210 I've found this thread saying it's a "random misfire, #3". But this code seems to be rare and there is not much information about it. So I haven't further looked into this one.

I looked into air/fuel and oxygen sensor. I found it a little weird that the air/fuel shows a .66V reading even if the engine is off, but it seems like that's the way it is. The thing I'm not sure about is when the engine is running and hot and racing, no matter what the air/fuel stays around that value. It slightly oscillates between .64V and .66V. I can see the full range of the sensor when I race the engine and get of the gas. The sensor then peaks up to .85V, falls to .55V curves back to .65V.

For the oxygen sensor I have seen different behaviors. I have seen something like a constant swing 0.85V and 0.20V to 0.40V. I have also seen a low signal as .12V with periodic peaks up to 0.85V.

Now, I'm sure it could be the catalytic converter. I did temperature measurements on it and it was 150 deg C before, 200 at inlet, 250 in the center and 200 at the outlet and after.

But before I go ahead and replace that, do have suggestions what I should check before? Could there be a problem with fuel pressure, ignition or injection causing those issues/symptoms?
 
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#4 · (Edited)
i believe the a/f sensor should ride around 3.3v at 14.7:1.
if it's at .6v and it's an a/f wide range sensor, then that's extremely rich.

the o2 sensor readings seem fine.

what are your long term fuel trims?

stopped up cat does cause sluggishness..


tony
 
#5 · (Edited)
The voltage range should be fine. I can't find it right now, but I remember reading something in the service manual, that with the Toyota tool you would read 3.3V while a regular reader would miss some factor and show .66V
 
#6 ·
if DC's correct and that .66v reading on the a/f ratio sensor is correct due to some obd reader discrepancy, then read out the long term fuel trims. if they're showing lean, then that combined with the hotter temps you recorded on the cat and the sluggishness you described would make me remove the cat and clean it out to see if it could be revived.
tony
 
#7 ·
Alright! I will take a look at the long term fuel trims tomorrow!

Another thing I just remembered is the rotten egg smell I sometimes have in the car, when going on heavy load like accelerating uphill. I read somewhere this would also be an indicator for a bad cat. Some metals that develop in there or so.
 
#9 ·
I was checking the fuel trims after I come home today, so engine was warm. I got following readings:

Idle (~700 RPM)
ST FTRM1 2.3%
ST FTRM11 2.3%
LT FTRM1 10.2%

Racing (~2750 RPM)
ST FTRM1 varying between -3.9% and 0%
ST FTRM11 varying between -3.9% and 0%
LT FTRM1 9.4%

I guess that is considered running lean!?

I watched some of Eric's videos before. As I remember he was testing different cleaning methods, but wasn't too convinced. Just checked out Scotty's videos and after that I thinking of getting a cheap exhaust gauge and do the back pressure test on converter and exhaust before I go ahead and take that thing of. Or I might try his "special fuel" cleaning method.
 
#10 ·
10% isn't going to trip a cel but it does appear you got a loose vacuum hose or cat backup or something leaning it out causing the ecm to add a bit more fuel than 0%.
yeah, lots of cat cleaning methods out there. i just bought a new one. costed 150 but in cali we don't mess with emissions. you don't get no slack here.
tony
 
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