Error codes on 1996 Discovery
 

I ran the codes today and two came up, P1187 and P1178. I have no idea what they are, and figured I could get the most reliable information and the best answers on what to do from everyone on here.

Your engine computer (ECM) monitors lots of things and makes adjustements to compenstate for wear on some parts, driving habits, etc. The 1178 code indicate you are reaching the limits of how far it can adapt things. But the 1187 code indicates an oxygen sensor has a problem with the heater circuit wire going to it. The O2 not operating could trigger the first code as well. Check connections when cool.

So based on that, have you ever changed your 02 sensors and how many miles on your truck?

I have only had the truck for about a week. The only thing I have done so far is put new tires on it. It currently has 137,000 miles on it. It was a one owner vehicle and the guy that had it before me took great care of it. The check engine light was so so I ran the codes. It also has the SRS light and ABS light on. The engine seems to be running perfectly.

Might want to list on the sticky posted at the top of this section and do a complete major service as spelled out.

Thanks, I'm defiantly going to do the major service. I am going to change out the O2 sensors this weekend and then start at the top of the list and get everything in shape. I really appreciate the help.

No Sir. No so lean, not so mean, but still a Marine. Never met one that wasn't.

Well I ordered the O2 sensors and when they arrived they were the wrong ones so I didn’t get a chance to replace them yet. I ordered a new set today. I drove about an hour away from my house in the truck to go camping this weekend. On the way there almost anytime I would put the truck in neutral to slow down the RPMs would drop very quickly and the truck would either want to stall or would. When I drove it home today it was doing the same thing. When I pulled up in my drive way the truck was idling very rough and slightly below 1000RPMs. The check engine light hasn’t come on again since I cleared the codes, but I ran them again and the only one that showed up this time was P1178. The only thing that I have done so far is put a new air filter on it as well as run a can of sea foam through the engine. I have also been putting the highest grade fuel in it.

Hi Mike,

I have a '96 Disco w only a check engine light and the P1178 code. How do I cancel them, (the code and check engine) light since no repairs are apparently needed. Truck runs great and just passed smog before check engine light went on.

Some parts stores will loan/rent code scanners. Many stores are not allowed to reset codes. You can also buy a nice one for $70, the Ultra Gauge. Willl read and reset codes, plus more.