I have just replaced my O2 sensors about a month ago. I am still getting codes 172 and 176, in addition to 181 and 189 (heated exhaust gas oxygen snesor voltage signal not switching indicates lean during part throttle engine operation) My question is what does that exaclty mean? I had a shop install the O2's if that was needed to know. A sympton I still have is a lot of hesitation when I drive, meaning I press on the accelarator and it does not go anywhere, just revs high. Another symptom is that after the engine is stopped and restarted within a short time period it would want to die which I read is a fuel injector problem but I just performed a sound test with a stethoscope and they all sound fine. Any ideas? I plan to just get my whole fuel system check but I want to know if anyone can pinpoint this problem I have? One more quesiton, if I am not receiving a code for say the TPS sensor can I assume that it is working properly or could could something still be wrong? I have been battling this for too long, any help is appreciated!!
Code question?
- Thread starter law
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law said:
mo_dingo
Dirt-Old 20+Year Member
After the O2 sensors were replaced, did the car IMMEDIATELY start this problem, or was the problem present before? Did replacing the O2's make any difference at all?
Here's my guess.
Does the car run like crap when it's cold also (i.e. when you first start the car in the morning after sitting for a while)? If it does, your O2 sensors are NOT THE PROBLEM.
The computer ignores the O2 sensors until the car completely warms up. They are Heated Exhaust Oxygen Sensors, meaning then need to be hot to work.
#1 - Vacuum leak. Easy check. Make sure you go over EVERY vacuum hose. That could cause serious unmetered air to enter your engine. Check to see if the gasket on the IAC valve is bad. That could also cause a vacuum leak.
#2 - Check the distributor cap/rotor. If the contacts are not clean, clean them. A flathead screwdriver can scrape and residue off and get it back to shiny metal. Bad spark can cause problems also. But I doubt that will solve anything.
#3 - Disconnect the battery, and leave it disconnected for 20 minutes. Then reconnect it, and drive the car for at least 20 miles. The shop may not have disconnected the battery when the installed the new O2 sensors. This will allow the computer to learn to function w/ the new O2 sensors. After 20 miles, the CEL light should come on if you are still having problems. Any codes you get now will be brand new ones.
#4 - One of your primary sensors could be bad. Meaning your MAF, IAT, ECT, EGR... Get a haynes manual, and check to see if the sensors are within spec.
http://www.usnaaaa.com/pingisgone.pdf
That document will help you test your IAC/ECT sensors to see if they are bad.
I have the book he is referencing from, so if you want the pages from the MAF/EGR, I will post them. I can't think of any other sensor that could be causing the problem. Remember, there are small variations in sensors each year. So you may see SLIGHTLY different voltage/amp/ohm readings than the book does. If you are off less than 3%, don't worry about it.
Your problem is very serious and a 3% difference is negligible. PM me if you want that information. You will need a digital multimeter to perform these checks. They run $15 at walmart.
Post back with any new info.
Scott
Here's my guess.
Does the car run like crap when it's cold also (i.e. when you first start the car in the morning after sitting for a while)? If it does, your O2 sensors are NOT THE PROBLEM.
The computer ignores the O2 sensors until the car completely warms up. They are Heated Exhaust Oxygen Sensors, meaning then need to be hot to work.
#1 - Vacuum leak. Easy check. Make sure you go over EVERY vacuum hose. That could cause serious unmetered air to enter your engine. Check to see if the gasket on the IAC valve is bad. That could also cause a vacuum leak.
#2 - Check the distributor cap/rotor. If the contacts are not clean, clean them. A flathead screwdriver can scrape and residue off and get it back to shiny metal. Bad spark can cause problems also. But I doubt that will solve anything.
#3 - Disconnect the battery, and leave it disconnected for 20 minutes. Then reconnect it, and drive the car for at least 20 miles. The shop may not have disconnected the battery when the installed the new O2 sensors. This will allow the computer to learn to function w/ the new O2 sensors. After 20 miles, the CEL light should come on if you are still having problems. Any codes you get now will be brand new ones.
#4 - One of your primary sensors could be bad. Meaning your MAF, IAT, ECT, EGR... Get a haynes manual, and check to see if the sensors are within spec.
http://www.usnaaaa.com/pingisgone.pdf
That document will help you test your IAC/ECT sensors to see if they are bad.
I have the book he is referencing from, so if you want the pages from the MAF/EGR, I will post them. I can't think of any other sensor that could be causing the problem. Remember, there are small variations in sensors each year. So you may see SLIGHTLY different voltage/amp/ohm readings than the book does. If you are off less than 3%, don't worry about it.
Your problem is very serious and a 3% difference is negligible. PM me if you want that information. You will need a digital multimeter to perform these checks. They run $15 at walmart.
Post back with any new info.
Scott
The reason for the o2 replacement in the first place was because I was receiving the codes 172 & 176 which indicates "lean" conditions in bank #1 & 2...other symptoms I had was pinging, surging, hesitation, and loss of HP. Since I am a begginer mechanic I had a muffler shop do the installation. After they installed them it has curred the pingin problem and surging, but there is still a lot of hesitation=loss of HP. I thought about the shop not disconnecting the battery so I did for 30 minutes and that still did not work. I just ran the codes yesterday and now I have two new ones that I did not have before (181 & 189)? The car starts up fine when it is cold, it never has a poor idle or anything only after it is considerably warmed up and I restart and stop it again and I always have the hesitation whether it is cold or warmed up. I will see if I have a vacuum leak and try testing those sensors you mentioned. You dont think it could be the fuel pump causing any of those problems I mentioned? I just bought one of those digital multimeters so I will see if I can do that.
Slow5.0
Active Member
Same problem here , 172 and 176 code , todat I try with new onw and nothing here is my post about that http://forums.stangnet.com/showthread.php?t=416460
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