check engine codes

[Goodtogo32]

I keep getting a check engine light with the code PO153 being shown. I know it's a slow OX sensor, problem is that this came up a month after I bought the car with only 9000 miles. I changed the sensor and it was OK for a couple of months then I had the clutch slave cylinder go and I had to have a clutch assy replaced with slave. Since then the chk light comes back on, if I reset it, it's OK for a week or so then it comes back. The connection is OK if he had to unplug it to drop the pipes. Any ideas, I'm about to put another new sensor in it.

[Vette40th]

Doesnt your C5 have 4 O2 sensors? Two in front of the cats and 2 behind them?
Check the pins on the connector, ensure they are not bent or pushed in.
Other than obvious wiring being burnt, cut.
If this is not the issue, you might want to check injectors for possible leaking..

[Goodtogo32]

I only see the 2 sensors, seeing this has headers and a Borla exhaust. How would I tell if I had an injector leaking? All the plugs look the same color.

[Vette40th]

Put a fuel pressure gauge on fuel rail. Runn engine, them shut off. See if pressure drops fast. Should hold for a while. That will tell you if injector or fuel pressure regulator is leaking. Thats it.
You car came with 4 sensors. 2 before cats actually tell ecm what to do. Two after cat were to let ecm know if cat is essentially working.
If they were eliminated, they the tuner deleted them so you wont get a code from back two.

[Ronins2ndCuzzin]

Did you replace it with an OEM AC Delco O2 sensor? Aftermarket (IE Bosch) sensors don't always play nice with ECMs.

[Goodtogo32]

I believe it was a Bosch, are they a problem?

[Vette40th]

I always used Delphi after my AC Delcos came in a box in a box, one saying China

[Goodtogo32]

once I check the fuel pressure and if I see a leak, how do I single out the offending injector?

[Vette40th]

You have to measure each one with a ohm meter, see if any are off from the rest. Not sure of ohm readings, but if one is bad, its reading will be obvious. Just out a meter across each post. There is low and high impedance injectors. Youra should be low. 1.7 to 3 ohms.
Once you do this,and nothing obvious with that or fuel pressure regulator draining fast, you will need to pull them and have them checked on a machine

[Goodtogo32]

Do you happen to know the # pressure stock injectors are? I may just get a new set, car was stored for 19 years. Just periodically checked on ( I'm hopeing). Still has the original battery.Thanks for all the help, I just noticed your from SC. At one time I was planning to move down there when I retired, a town called Chapin.

[Vette40th]

Not sure the factory# inj. I went here last time , years ago. Very good customer service.
https://fuelinjectorconnection.com
Chapin is nice. Most of SC is nice, laid back, lower cost of living.

[Ronins2ndCuzzin]

Originally Posted by Goodtogo32

I believe it was a Bosch, are they a problem?

Simply put, GM ECU's do NOT like O2 sensors that are not OEM. They have caused all sorts of issues for many folks in the past.

[Vette40th]

Who makes GM sensors?. My ac delcos, a couple years ago, had a made in China box within the box.

[Goodtogo32]

In my opinion SC is one of the nieces places on the east coast and I have visited from Maine to Fla. I used to be an avid Bass fisherman and my best friend and I ether camped or found a place to rent to stay. Another life, ya know.

[Ronins2ndCuzzin]

Originally Posted by Vette40th

Who makes GM sensors?. My ac delcos, a couple years ago, had a made in China box within the box.

As long as it's branded AC Delco (or Delphi depending on year) it should be fine.

[Goodtogo32]

What do you think of this Vette40th? Before it was just a PO153 code, NOW I'm getting both PO153 and PO133 every now and then it seems to alternate back and forth. The left side is a factory OEM. I know they are 20 years old but this car was stored for 18 of those years. I'm beginning to suspect a voltage problem.

[Vette40th]

Originally Posted by Goodtogo32

What do you think of this Vette40th? Before it was just a PO153 code, NOW I'm getting both PO153 and PO133 every now and then it seems to alternate back and forth. The left side is a factory OEM. I know they are 20 years old but this car was stored for 18 of those years. I'm beginning to suspect a voltage problem.

Can you put a real time scanner on there? OBD2 scanner and watch the O2s. They should be fluctuating quite a bit at idle.
Swap left to right sensors and see of the problem moves.

[Goodtogo32]

I would like to get a scanner on it when it happens, but I'm limited in that respect. Now follow my logic, the problem always occurred when I got on it hard thru a couple of gears and when I decelerated the lights would come at that time. If I charged the battery to 90% by the next morning it would be down to 40%! So I finally put in a new battery the other day and now I haven't gotten a light while it was a daily thing before. All I could think was that the old battery was not putting out enough voltage and when you let off the gas at high RPM the alternator wasn't catching up. Let me know what you think
PS I didn't bother swapping O2's because I was getting both codes.

[Vette40th]

You should be running off the alternator when driving. I am no expert in that, but, its possible you had a bad battery that was causing the alternator to overwork?.
I know new cars are sensitive to voltage at start up..
Give it a few days and keep trying to simulate the same thing you did to cause the error.
A good scanner that has real time data is invaluable..

[Goodtogo32]

The chk eng lite came on today with a PO153 code. After I put a new battery in it went 4 days with out a code when it was a daily occurrence before, it may have been a coincidence and I'm just fooling myself. I'm going to have to find a professional with a scanner