OBD Code 44 - Troubleshooting?

[rob_83k5]

Hi,
Only had my truck (see sig) a couple of weeks and although it seems to be running fine, I get the 'Service Engine Soon' light coming on intermittently. I checked for the codes and it's just showing code 44 - which I looked up and found it's 'the O2 sensor is showing a persistently high exhaust oxygen content (lean)'.

Could someone give me an idea of the best way to troubleshoot this?

Cheers

 

[crazedyak]

The manual says:

1) Check O2 sensor wire (purple wire from ECM to Sensor pin D7)
2) Check the ground (tan wire from ECM pin D6)
3) Possible water in fuel
4) Fuel pressure too low
5) Faulty O2 sensor

One of those is the most likely culprit

 

[rob_83k5]

Thanks for that, I found a similar list with these recommendations:

++ Check the wires of the oxygen sensor, making sure they are not in contact with the exhaust manifold.

++ Check the oxygen sensor and replace if necessary.

++ Check the MAP sensor. If the ECM detects a higher than normal vacuum then this will cause the system to go lean. Disconnect the MAP sensor. If the lean condition goes away, then a problem exists with the MAP sensor.

++ Check for lean injectors.

++ Check for fuel contamination (specifically for contamination with water).

++ Check fuel pressure. If pressure is too low, the system will be lean.

++ Check for exhaust leaks. An exhaust leak can cause air to be pulled into the exhaust and past the sensor.

My first step was going to be checking the O2 sensor wire, and possibly trying a replacement sensor (as the engine is actually running perfectly ok) - however, I checked the exhaust from manifold to the back box (there is no cat) and there's no sign of an O2 sensor anywhere!! I'm beginning to suspect that someones replaced the exhaust and used some sort of work-around rather than welding in a fitting for the sensor (is that even possible?) ....and if that's the case then what on earth am I supposed to look for (a pointer to where the ECM is located would be a help)?

 

[dyeager535]

O2 should be in the exhaust manifold. Obviously if it's missing the cat, someone has screwed with the exhaust, so possible they had bad manifold(s) or something and used older, never replacing it.

Oddly, it does seem that missing O2 sensors don't always trigger a code continuously. Odd, because you'd think that a component that critical to operation would be "noticed" by the ECM if not working properly as soon as the engine warmed up.

ECM is above the glove box. Drop the glovebox, look "above" where the glovebox sits and you'll see it. Possible the PROM has been swapped out, but I've not heard of anyone commonly selling one that has an O2 sensor delete, that's pointless. You can remove two screws on the cover and take a look, the piece under it, if aftermarket, will say "hypertech" or "jet", or whatever from y experience. Otherwise it will just be a blue plastic piece closest to you, with some numbers and letters visible through the holes in it.

 

[rob_83k5]

Thanks for the pointer - I managed to find the O2 sensor, in the back of the manifold on the drivers side (next to the oil filter). I'll be ordering a replacement tomorrow and take it from there.

 

[4xcrazy]

Get yourself a new, better quality oil filter as well..

 

[rob_83k5]

Ah, you noticed
....I suspect some basic servicing is required