SES light and codes shown

[Wild Driver]

My SES light came lit up on my '99 Discovery. The codes shown are as follows:
PO455-evap emission control leak
PO154- O2 bank 2
P 1590 Undefined
Any ideas what these indicate?
Thanks in advance for any help.

[DiscoAmigo]

PO455-evap emission control leak-Maybe a lose gas cap or vent line.
PO154- O2 bank 2-Possible short, check the connection on the O2 sensor (front RH sensor)
P 1590 Undefined-ABS rough road signal, probably nothing to worry about unless you have other ABS warning lights.

Hope this helps

[Wild Driver]

Is that the O2 sensor on top of the exhaust pipe that has an orange connector about half way up? BTW, thanks for the response. Also, I'll check the gas cap, but is there vent line from the tank? And, how would I reset the P1590 code about the ABS system. I have no other lights on but do live on a rough dirt road as you mentioned.

[Wild Driver]

Interestingly, everything was going along with no light on until I replaced the fuse for the windshield washer pump????????????????????? Then the SES light came on.

[Disco Mike]

How many miles on your truck?
I believe the 1590 code can be cleared with a simple hand scanner, the other two will need to have corrections made prior to clearing them.
Mike

[Wild Driver]

It has about 136k according to the old owner and the title. The odometer has blinked since I got it and it reads about 30500. The light just came on as I mentioned after I installed a new fuse for the windshield washer. I drove it for a while and no lights were on.

[Disco Mike]

Well at your mileage, if the 02's haven't been replaced yet, they are sure ready, it will get you some better mileage and performance.
Mike

[buick215]

Originally Posted by Disco Mike

Well at your mileage, if the 02's haven't been replaced yet, they are sure ready, it will get you some better mileage and performance.
Mike

Mike,are you a rep for NTK ? Just because the truck has a few miles on it there is no need to change them just for the sake of it.Get them tested,yes - to make sure all is well.But replacing them at a set mileage is wasteful,they are capable of much higher mileage on well serviced truck.Correct diagnosis is what we all should be looking for,as a garage operator I would rather charge for testing and passing components than just swopping them out for the sake of it.The customer is happy the truck is Ok and we are all happy not to waste rare metals.

[Wild Driver]

Ok
I can't find any emission leak. I've checked the cap and tried to find something under the LR that might be loose. Any other suggestions? I checked the connection on the 02 sensor and took the sensor out and cleaned it before resetting the codes, so we will see. I have reset the code 1590 on the brakes twice but it keeps coming back, anymore ideas on what that could be? Thanks in advance.

[Disco Mike]

Bottom line, cleaning won't help old 02's like your, replace them.
As for the evap leak, you'll need a mechanic to test for that.
Same for the ABS, you need a pal top type scanner to clear the ABS faults.
Mike

[ArmyRover]

Buick215 it's throwing a o2 sensor code 136k+ or maybe even more since it has a broken odometer. I would say you don't have to be a NTK rep to say it's time for some o2 sensors.

[buick215]

Thanks for the PM Disco Mike,I have nothing to hide or prove,my response to this post still stands,oxygen sensors are an expensive replacement,many are changed with no good reason.If owners of cars actually understood what was going on it would give them even more ammo to throw at a trade that gets enough stick already.
Testing the sensors to see if they are capable of switching and are being heated should be the first port of call with this car - NOT just swapping them.
If they are capable of switching there is no point in changing them as the codes will come back,what needs doing then is looking for the reason that they arent switching during use,inlet/exhaust leaks,dribbling injectors etc.
How stupid would a garage look if they just swapped out sensors and the light comes back on ?
My experience - as you ask, is from running a LR shop for 25 yrs with Testbook 1 and 4, 2 oscilliscopes and many thousands of pounds worth of other diagnostic kit.Alot of my work is for other LR indy's and the cars often end up with me after loads of new parts have been fitted and the car is no better.Correct diagnosis will gain better customer respect and more repeat business than throwing parts at cars and still not fixing them.

[Elemental]

Originally Posted by buick215

Correct diagnosis will gain better customer respect and more repeat business than throwing parts at cars and still not fixing them.

Read it, Learn it, live it, love it!

This is gospel!

[KDamericano]

Speaking from a shade-tree mechanic perspective, I do agree that there's a lot to be said for correct diagnosis. However, in this case, I'd just replace the sensor. I had one go out about 4 months ago. Threw 2 02 sensor codes. I don't have an oscilliscope (it's next on my list), so the process of checking an 02 sensor for me involves climbing under there, reverse-probing the wires at the back of the sensor, and watching my volt meter - all the while trying not to get burned by the exhaust. The cheapest shop rate around here is usually about $80 for a diagnosis. The 02 sensor at napa was $65. It really just made more sense to replace the part. Had the codes come back, then it's easy enough to either return the part, or keep in on the shelf since there's a decent chance you'll need to replace one eventually anyways. I think it's refreshing to see 2 mechanics with the perspective of elemental and buick. But that's also your livelihood, so you're going to be of a different opinion than the average person who is not worried about repeat business or a reputation. You've also got all the tools at your fingertips to make a proper diagnosis. My guess is that Wild Driver does not.

[buick215]

Originally Posted by KDamericano

Speaking from a shade-tree mechanic perspective, I do agree that there's a lot to be said for correct diagnosis. However, in this case, I'd just replace the sensor. I had one go out about 4 months ago. Threw 2 02 sensor codes. I don't have an oscilliscope (it's next on my list), so the process of checking an 02 sensor for me involves climbing under there, reverse-probing the wires at the back of the sensor, and watching my volt meter - all the while trying not to get burned by the exhaust. The cheapest shop rate around here is usually about $80 for a diagnosis. The 02 sensor at napa was $65. It really just made more sense to replace the part. Had the codes come back, then it's easy enough to either return the part, or keep in on the shelf since there's a decent chance you'll need to replace one eventually anyways. I think it's refreshing to see 2 mechanics with the perspective of elemental and buick. But that's also your livelihood, so you're going to be of a different opinion than the average person who is not worried about repeat business or a reputation. You've also got all the tools at your fingertips to make a proper diagnosis. My guess is that Wild Driver does not.

Thats a fair comment and I appreciate your interest,I'd just like to add two further points,first is I cant see any parts supplier taking back a "slightly" used sensor.Secondly our man can obviously read or get codes read,(I understand this can be done for little or no cost in the US,here in the UK you still have to pay ! ) so why not try swopping the front sensors from side to side and see if the codes follow the sensor ?
I suppose what really bugs me is the obvious lack of understanding of recent EFI systems,whilst they appear complex and having the kit I do makes life easier,there is still a great deal that can be done with a simple multimeter.The functionality of the systems is well documented and easy to access.