Engine Soon:Mercury Topaz 1994 wet weather or rainy day

My old car is having some age and needs a computer checkup for an error on the dash board saying Engine Soon. The problem just show up this month and happen in the morning of wet weather or rainy day. The light will disappear when the engine is hot,dry and driving at the same time. The light will most likely show up when engine is idle,cold in wet weather. This is summer. I don't want to see this fall.

Before going to the garage and believing those mechanics. What could be the problem? it sound to me a sensor. May the oxygen sensor or the thermostat getting faulty.

This sound a common problem on those model , especially for car sleeping in the garage moist temperature. My car is sleeping outside. Any mechanic went in this situation before? Please assist and remember I am not a mechanic, please be detail and patient.


Mercury Topaz 1994
2.3 L , 5 speeds
160 000 km

Hello. First, click here and see if you can retrieve the trouble codes. Then scroll down to see what the code meaning. This is a starting point only. Please post back with your results and we can help you more. Welcome to our forum.
 

The good news, the engine soon disappear by itself for the last week and a half.

What I did so far.
Get the haynes repair manual for this car.
as you told me use a voltmeter to find the trouble code.

to make sure it was hookup ok:
I used a mastercraft digital meter set to 20 DC Volts and used gauge 14 electric wire.
I followed the schema and make sure each connection were ground properly in pin or at the battery.
when key is off position, I get 12.50 volts on meter. telling me it ground ok all place. if I took off the probe from the plus battery meter come to 0 volt

for reading on digital meter , I only use the last 2 digits after the dots,when set to 20 v dc.

Ok so far, but the problem start now because I don't get the same answer

when ignition key turn on,engine off I end with code 59,61,62. it is not constant when I repeat the steps every 5 mins. That is what is tricking me to give the accurate reading.

when engine turn on. I got the code 14 steady. When I try back later 14 never came back at all and switch to 19 or 21

in conclusion I will have to wait until engine soon come more often. and needs the help of a mechanic to get the accurate reading.

according to the book.
19 erratic idle speed or signal when engine is on.

if 19 or 20 ,that is the right problem, I think only the dealer could fix it with his computer tools.