Codes P0300-P0302, P0740, P1399

DEVONPEARL18

MEMBER
1999 HONDA CIVIC
1.4L
2WD
AUTOMATIC
170 MILES

I was driving and CEL comes on and then start to notice the temperature gauge, hesitate to reach the middle, and after five to seven miles the temperature skyrockets, CEL starts blinking, and burning smell fills the air. Went home, read the codes, P0300-P0302, P0740, and P1399, popped up. Went to restart the car after five minutes, and engine would click, but not turn over. Let it sit for fifteen minutes, and then started back up but motor shaking, and will not idle around 1000 rpm and then drops and car stalls. Could it just be faulty plugs or possibly a problem with the valve gap being too small? Help please!

1 Reply

STEVE W.

MECHANIC
13,465 POSTS

P0300 = Random multiple misfire.
P0302 = Misfire detected, cylinder number two.
P1399 = Honda code for multiple random misfire detected.
P0740 = Torque converter clutch control circuit malfunction.

Common causes for misfires are low fuel pressure, vacuum leaks and bad fuel.
In this case the sticking the rapidly rising coolant temperature also suggest another failure that will cause misfires, a bad head gasket.

First thing I would do would be to visually check if a section of the wiring harness fell onto the hot exhaust and melted the insulation, that would give you a bad smell, could also create the no start if the wires shorted as well as the misfire codes. It happens more often than it should.

I would next check the actual coolant level. If it is very low it could easily create a spot inside the engine where the temperature sender is located which fed a "wrong" signal to the gauge as the sender needs coolant around it to show the true temperature, suddenly water entered the spot and the instant cooling cracked the head or a blown head gasket.
Here are a few tests that you can try to see if this could be your problem. If it is then you will need to decide how you wish to proceed.
https://www.2carpros.com/articles/head-gasket-blown-test

I do not think it is the valves because it was a rapid onset vent. Bad valve clearances will slowly get worse over time, not suddenly fail.
It could be a couple bad plugs but I would expect to see two cylinders listed not the random code. Also, a bad plug or two would not create a burning smell.