1987 reliant le 2.5 my trouble codes are , 1.2 , 1.3, 5.5 what does this mean?

1987 vehicle & all those problems

Time to get another car

Code 13 (1 flash,pause,3 flashes) is "MAP Sensor Signal Not Changing". This could be something as simple as broken vacuum line from the intake to the MAP, the factory line used in the Reliants is usually hard plastic, with rubber hose joining it to the Intake & MAP. It gets very brittle with age and tends to fall apart or break from engine movement/vibration/hot-cold cycles/etc. It may also be a poor electrical connection at the MAP Sensor, or even a MAP failure.

Code 26 (2 flashes,pause,6 flashes) is Injector Current Peak Not Reached or Injector Short or Injector Open. This is most likely related to Code 13 that I mentioned above, as well as Code 52 which I'll detail next. The fuel injection system relies on input from the MAP, IAT, Engine Temperature Sending Unit, etc to control the injector

Code 52 (5 flashes,pause,2 flashes) is Engine Running Rich. Definitely related to Code 26, which is most likely related to Code 13. One part can cause a whole chain of issues in the injection system.

Code 55 (5 flashes,pause,5 flashes) means "End of Codes". No more codes have been found.

As for the other things you mentioned; overheating, the overflow jug being filled to the top, and consuming oil. I think you have some more serious problems going on there. It may have blown a head gasket when it overheated. Which could cause Compression to push past the fire ring, into a water jacket, forcing coolant out of the radiator into the overflow jug. There's 3 obvious signs for a blown head gasket, though sometimes you only get one, sometimes you get two signs, sometimes you get all three. 1 I just mentioned, 2 is consuming coolant (the engine will draw coolant into the combustion chamber and partially burn it and expel the remains out the exhaust), 3 is the mixing of coolant and oil, where coolant passes between the water jackets and oil ports, mixing. The usual sign for that one is a peanut butter colored goo on your dipstick or oil cap.

If it overheated to the point where the engine shut down (like you said), it may have damaged the piston rings, which would result in excessive blow by and oil consumption. I've seen this happen quite a few times on various engines

I would recommend performing a Leak Down Test and a Compression Test so you can determine what you're dealing with.

i think it is built in

1= You must test the ignition syste, reset the ignition timing see the diagram
2= Test the fuel pump
God bless you

You need to do the on board diagnostics to determine what trouble code(s) it is giving. Here's how: cycle key to On (not start) position, then off, then on again, then off, then on, and leave it in the on position. (leave on after 3rd time on ) Now the check engine light will flash a series of 2 digit numbers, with a pause in between each digit. For example: 2 flashes, pause, then 2 more flashes, would be code 22. 3 flashes, pause, 5 more flashes would be 35. There will also be a little longer pause between the 2 digit codes. You may have more than 1 trouble code, so pay attention and write them down as you go. When you get code 55 ( 5 flashes, pause, 5 more ) that means end of message, or codes. Get back to me with those codes and I will tell you what area the codes are pointing at as a problem. Does the car seem to be experiencing any running problems currently?

Has the "check engine " light come on? Are you familiar with the procedure of cycling key on, off, on, off, on and retrieving any trouble codes? Black plugs indicate a rich mixture. Couple of things come to mind but lets see if any codes first.

If you just changed the battery, or had it disconnected, 11 will disappear next start and run, 12, is telling you that the battery has been disconnected recently, and should disappear as well in 15 or so starts, and 55 is end of message, you will always get that.
If it's a no-start situation, check connections, wires etc at distributor, as well as pick-up plate inside under cap and rotor.

firing order is 1-3-4-2. cylinders are 1-2-3-4 starting from left as you are standing in front of the vehicle.

Have you tried cycling key, to on, off, on, off, on, and leave on and count the flashes of the check engine light?
(Just to on, not start) This should retrieve any trouble codes. Write them down & get back to us. It will be 2 digits and will work like this example: 2 flashes, pause, then 2 more flashes= code 22. 3 flashes,pause then 5 more flashes would be code 35. Code 55 means end of message.

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