Check engine light: P0133 & P0153
Thread Starter
Le Mans Master
Joined: May 2005
Posts: 6,366
Likes: 249
From: Fort Lauderdale, Florida
Check engine light: P0133 & P0153
Recent codes popped up, not sure but do I need new 02 sensors? Once cleared will stay off a little while, then one day I'll start the car and they'll come back on. Exhaust stinks real bad and gas mileage is down, plus I replaced the sensors around a year ago. I had installed AC sensors but at the time I installed them I saw no improvement. Should I try Densos this time if that is what I need? Also, unless its my imagination more likely to happen when the car is cold and the weather is cool out. Fortunately I've gotten good at deleting codes while I'm driving so I don't have to keep staring at a check engine light. Last thing to mention, I've got LG headers with deleted front 02's and the rears moved forward. My car has run fine for quite a long time like this, this is a more recent thing. I also deleted my air pump system which was tuned out by Doug at ECS. Car passes NJ inspection set up like this. Any help or suggestions?
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,621
Likes: 4,069
From: Cape Coral, Florida
Happy Memorial Day !!
First thing I would find someone that has a scan tool that can graph and see what your O2 sensor waveform look like...I enclosed a pic of what mine look like but since you deleted your downstream sensors you would only see your upstream (banks 1/2 sensor 1) switching between 100-900 Mv...with you smelling exhaust the sensors are most likely reporting lean (low Mv) and driving your fuel trims WAY positive...could be sensors or could be wiring...most GM's and I believe our C-5's have an O2 sensor bias voltage...if you disconnect the O2 sensor harness when cold the O2 sensor would show constant 450MV on a scan tool. If you see this your wiring is OK. Now you also mentioned this happens when the car is cold...could be your intake manifold leaking...this is more evident when cold but when the car warms up metal expands and the leak seals itself up...again with a scan tool your fuel trims will start going negative as you increase the RPM to 2500-3000 and the car runs better.
First thing I would find someone that has a scan tool that can graph and see what your O2 sensor waveform look like...I enclosed a pic of what mine look like but since you deleted your downstream sensors you would only see your upstream (banks 1/2 sensor 1) switching between 100-900 Mv...with you smelling exhaust the sensors are most likely reporting lean (low Mv) and driving your fuel trims WAY positive...could be sensors or could be wiring...most GM's and I believe our C-5's have an O2 sensor bias voltage...if you disconnect the O2 sensor harness when cold the O2 sensor would show constant 450MV on a scan tool. If you see this your wiring is OK. Now you also mentioned this happens when the car is cold...could be your intake manifold leaking...this is more evident when cold but when the car warms up metal expands and the leak seals itself up...again with a scan tool your fuel trims will start going negative as you increase the RPM to 2500-3000 and the car runs better.
Thread Starter
Le Mans Master
Joined: May 2005
Posts: 6,366
Likes: 249
From: Fort Lauderdale, Florida
I would think that smelly exhaust would be from running rich, no? Car is running okay but I think it seems a little sluggish, not positive about that? Will a Tech II show the info you are referring to? I have my own. I haven't used it to diagnose my car yet, I've just been going by the DIC messages. When I get the codes the DIC says Current, but there is no History indicated. It might read "PO153C". I haven't had any other problems, otherwise running great. Think I should go ahead and replace the 02's? I read on this forum people had good luck with the Densos I mentioned.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,621
Likes: 4,069
From: Cape Coral, Florida
Yes, smelly exhaust would be rich...black exhaust smoke but it sometimes can be white...a lot of people diagnose it as a blown head gasket. A Tech 2 should definitely show LIVE DATA and you should be able to see current codes and history...I use an Autel scan tool and also a 2 channel Picoscope (oscilloscope) and a Snap On Vantage Pro which is great for troubleshooting ignition systems, relative compression, cam and crank signals and a whole lot more...you should have freeze frame data which will show all the data PIDS when the code set...really helps in diagnosis...I did check my O2 harness unplugged and I do have 450 Mv which means my sensor wiring is good...I enclosed a pic and I'd probably stick with OEM sensors...that's what they designed the car with !!
Advanced
Joined: Oct 2014
Posts: 95
Likes: 17
From: Colorado Springs Colorado
I do periodically get the P0133 code so I am interested in this thread. I am new to the car and it does smell like it runs rich at idle...but I suspect its do to the tune because of the TSP Tsunami cam. I have not had a chance to do any troubleshooting at all yet. It has happened twice (I have only been driving the car for a week) and both times were while cold. The car does not idle high when cold which I again attribute to the tune. There are no downstream cats, similar to you, but unlike you, my gas millage is actually really good...at least while driving down a road.
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Recent codes popped up, not sure but do I need new 02 sensors? Once cleared will stay off a little while, then one day I'll start the car and they'll come back on. Exhaust stinks real bad and gas mileage is down, plus I replaced the sensors around a year ago. I had installed AC sensors but at the time I installed them I saw no improvement. Should I try Densos this time if that is what I need? Also, unless its my imagination more likely to happen when the car is cold and the weather is cool out. Fortunately I've gotten good at deleting codes while I'm driving so I don't have to keep staring at a check engine light. Last thing to mention, I've got LG headers with deleted front 02's and the rears moved forward. My car has run fine for quite a long time like this, this is a more recent thing. I also deleted my air pump system which was tuned out by Doug at ECS. Car passes NJ inspection set up like this. Any help or suggestions?
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,621
Likes: 4,069
From: Cape Coral, Florida
I do periodically get the P0133 code so I am interested in this thread. I am new to the car and it does smell like it runs rich at idle...but I suspect its do to the tune because of the TSP Tsunami cam. I have not had a chance to do any troubleshooting at all yet. It has happened twice (I have only been driving the car for a week) and both times were while cold. The car does not idle high when cold which I again attribute to the tune. There are no downstream cats, similar to you, but unlike you, my gas millage is actually really good...at least while driving down a road.
To help you in your T/S for a P0133:
• A faulty O2 Sensor
• A leaking exhaust manifold
• An engine vacuum leak
• An open or short in the wiring of the O2 sensor
• Soot or oil buildup on the O2 sensor (excessive buildup will clog the ports the sensor uses to measure the air fuel ratio)
• A dirty mass air flow sensor
• Incorrect fuel pressure
GOOD LUCK !!!!!
Last edited by C5 Diag; Jun 1, 2018 at 03:04 PM.
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