First post here guys! I bought a 2003 LR Discovery SE7 about a month ago and have been tinkering on it to bring it up to snuff. So far, I have fixed coolant pipe leaks, changed oil, replaced the Evap purge valve, MAF sensor, and degreased the engine. I had tried to clean the old MAF with no luck, so I bought a new MAF (no name from Ebay) and cleared the codes. All was well until I degreased the engine. Check Engine light came on within 3 miles resulting codes were p0135,p0150, and p155.

Any help is appreciated!

 

Never use a degreaser to clean the entire engine, it will get into to your connections and cause you grief. How many miles on the engine, what color are your plug wires? Might want to clean your 02 connections with electrical contact cleaner then use some die electric in them, if that doesn't work, you may need to replace them.

 

The engine has 108K on it and was running well before this. The plug wires are grey and were just replaced before I bought the truck. The O2 sensors were replaced at 106K by a previous owner.

Is there any way to check the O2 sensors without replacing them? I have an OBDII reader that links to my lapotop that is expected to arrive today. I think it has 'live' sensor readout.

Thanks in advance!

 

Yep there are voltages that change. However, you connectors are likely full of moisture from the cleaning, so open them up and spary electric circuit cleaner in there and use some dielectric grease when you put them back togther. Here are some pages from the Bosch ECU manual that tell you what voltages to expect for the codes. Some O2 voltages change normally and constantly. What you sprayed in there is now trapped inside and may cause corrosion.

You'll do better with new silicone plug wires, 8mm are better (last longer). Old gray wires break down easily and cause misfires.

 

If your scanner shows real time information, you can check on their activity and compare that to what the Rave shows they should be.
Grey wires are either factory or cheap after market, they will let you down and throw mis-fire codes at some time, so when they do, as Buzz has also mentioned, replace them with something like 8 mm STI or Magnecors.

 

Just reset the codes.
Drive it 10 miles.
The water will burn off the engine.
All will be fine.
After the 10 miles reset the codes again.

After that there should be no codes.

I put engine cleaner on my engine --- Gunk engine cleaner and 3M
in Boulder CO.

I put that on, let it sit and then used a pressure washer to pretty up the engine.
I never got any codes.

And I sprayed the engine pretty hard.
And used two cans of engine cleaner on it.

I guess as all are saying - this is a RISK and you may come out OK, you may not.

 

I must say that some CRC Wire Dry, compressed air, dielectric grease, and the ELMSCAN 5 works wonders. Thanks for your help!

BTW, I found that the ELMSCAN 5 is a nice product and is very inexpensive to monitor your system and clear codes easily from a laptop.