o2 sensor
Thread Starter
Intermediate
Joined: May 2006
Posts: 38
Likes: 0
From: Gilbert Az
o2 sensor
I have a new o2 sensor installed on a 89 vette. It only has the one on the left side of the engine. But the computer keeps throwing an o2 code at me (dtc 44). I tested the o2 sensor and with the engine warmed up and running the voltage on the o2 starts high and runs way low and stays there. can any one tell me whats up.
Safety Car
Joined: Sep 2003
Posts: 3,598
Likes: 23
From: Orange County NY
St. Jude Donor '10-'11-'12-'13
Voltage from the O2 sensor should oscillate from .1 v to .950 v, with .450 being about a 14.7:1 air/fuel ratio. Voltage lower than .450 is lean. Code 44 indicates a lean condition.
Pull a few plugs to verify that it is running lean, then start troubleshooting the lean condition.
Pull a few plugs to verify that it is running lean, then start troubleshooting the lean condition.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Code 44 is "Lean Exhaust Indication". You will need a FSM and a scanner to diagnose truely diagnose the problem. As stated above pull the plugs and verify it is running rich. Look and make sure the O2 sensor pigtail (purple wire) is not touching the exhaust and the ground (tan wire from the ECM) is tight and corrosion free.
You can try Field Service Mode by starting the engine and inserting a paperclip/code key into terminal A and B of the ALDL and the SES light will start flashing. Once a second for normal, off more than on for lean, and fast flashes or on more than off for rich. In open loop operation (exhaust temp < 600*) the O2 sensor is not used and the car basically runs rich. After the criteria is met the ECM goes into closed loop and mainly uses the O2 sensor for fuel demand.
Easy to understand...eh.
You can try Field Service Mode by starting the engine and inserting a paperclip/code key into terminal A and B of the ALDL and the SES light will start flashing. Once a second for normal, off more than on for lean, and fast flashes or on more than off for rich. In open loop operation (exhaust temp < 600*) the O2 sensor is not used and the car basically runs rich. After the criteria is met the ECM goes into closed loop and mainly uses the O2 sensor for fuel demand.
Easy to understand...eh.
Safety Car
Joined: Sep 2003
Posts: 3,598
Likes: 23
From: Orange County NY
St. Jude Donor '10-'11-'12-'13
Under normal operation, the porcelain insulators should have a light tan coloration. When the engine is running lean, they will be bone white. (On the flip side, when the engine is running rich, they will be almost black).
Since the O2 is new (and assuming it is good), I'd say something is causing the engine to run lean. Do you have access to a scan tool? It would show you if the ECM is trying to correct this condition (BLM and INT numbers) once in closed loop. Sometimes, a lean condition is a result of poor fuel delivery. How does the car run?
Since the O2 is new (and assuming it is good), I'd say something is causing the engine to run lean. Do you have access to a scan tool? It would show you if the ECM is trying to correct this condition (BLM and INT numbers) once in closed loop. Sometimes, a lean condition is a result of poor fuel delivery. How does the car run?
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Seems like your have a problem in the combustion process. Maybe a stuck closed injector(s), exhaust leak before the O2 sensor, vacuum leak. The best way to start finding a problem is to pull the plugs and observe the color and smell (start on the left...that's where the O2 sensor is).
