Engine light on do to coolant system problem.. car runs great...got it tested they said some code for the cooling system..please help if you know.. thanks...

1. Make sure the electric radiator fan(s) is kicking in when the coolant temperature gets hot. If not that will be part of the problem and if the temperature sensor/switch is faulty the fans may not operate.

2. You may have a restriction in the cooling system that is significantly retarding the flow of coolant through the engine coolant passages or through the radiator. This can be caused by a build up of debris in the system so you cannot achieve optimum coolant flow.


3. You may have a combustion leak via a failed cylinder head gasket into the cooling system. This will cause hot combustion gasses to flow from the cylinder into the cooling system and the coolant will overheat. Bubbles showing up in the cooling system is a possible indication of that. A leak down test will show this up. This involves blowing compressed air into the cylinders one by one through the spark plug openings. If air enters the cooling system in this test bubbles will appear in the coolant and it is a sign of a failed cylinder head gasket and that combustion gasses are able to escape into the cooling system when the engine is running.

4. THE rough idle may be a low RPM miss fire in one or more cylinders. You need to have the vehicle scanned to see what fault codes the computer is generating. If you have rough idle once the engine has warmed up there will be one or more fault codes being generated. Once scanned and all the fault codes are found, the cause of the fault codes can be investigated and the problem fixed.



5. Do not hesitate to have the problem of the overheating checked out. Running the car with the engine overheating WILL cause expensive engine damage many times more than it will cost to fix the problem now. If you have been running the engine frequently in an overheated condition you may well have already caused failure of the cylinder head gasket but I hope this is not the case. Running the engine overheated can also cause the cylinder head to warp and crack. These are expensive engine repairs you definitely want to avoid.

6. You did not indicate the year, model of vehicle and engine type you have. Please provide this information if you have future questions as this normally has a direct bearing on the content of answers people are able to provide.

Have competent mechanic pressure test cooling system to find leak.

You need to have your cooling system pressure tested. This will let you examine the engine area without the hazards of the engine running. You may have head gasket issues. Depending on the area of the leak, your cylinder compression can actually pressurize the cooling system. When the cooling system pressure exceeds the rating of the cap, the cap seal opens and can blow coolant back into the overflow bottle where it eventually leaks while driving. Check to see if your overflow bottle is full.

Coolant reservoir has two level marks printed on it. LOW and HIGH.
At room temperature add the coolant up to low level. Close the cap, and start the engine till radiator fan comes on. The coolant level will rise to High level mark and then come back to low. If it is so it's OK. If the coolant level consistently drops below the low level, make two more attempts in maintaining the level to bleed the air from cooling system.
If the problem persists consult a good technician.

If this ever happens again turn the internal heater to full, it helps in the cooling. When filling the engine with coolant the heater should be on full. As the engine warms squeeze the top radiator hose regularly to encourage air bubbles to shift to the expansion tank. If the coolant level looks low after the engine has been brought to full running temperature and air has been purged from the system then top up with additional coolant. Note that the signal to run the fan is sent by the coolant sensor, if the coolant is low the sensor cannot function. Check your engine error codes, sometimes if the coolant sensor cannot detect normal running temperature (perhaps due to low coolant level) the engine is unable to enter closed cycle mode and reports p0125. Closed cycle is the normal running state of an engine at normal running temperature; open cycle denotes the times when the engine is cold such as at start up or when the engine is under load such as when accelerating hard.

add coolent, your coolent is low your heat will than return dont forget to check for leaks. cooling system should be tested with a cooling tester.you may have to take it to a radiator repair shop to have it tested..

Sounds like you have a faulty head gasket or maybe a cracked head.This can cause overheating and the check engine light to come on.The code for the o2 sensor is probably caused by coolant getting into the exhaust system and coating the sensor.The coolant fan may work but it cannot remove enough heat from the rad to make the engine cool off.Try some engine coolant stop leak to see if it will help.This maybe only a temperary fix.Let me know if you need more.MOE

What about the possibility of a crack in head gasket between oil passages and coolant passages. Oil pressure would be higher than cooling system pressure, thus oil would be more likely to enter cooling system, than coolant enter oil /lube system. Just a thought. Have you done a cooling system pressure test, just to see if any drop at all in pressure? Seeing how engine would not be running, oil pressure would be 0, and may allow coolant to seep through same path, only from cooling system, to oil. Is it a large amount that your getting?

have u bled the cooling system ?warm the car and cut the car off right before the fans come on ,let sit for 30-35 minutes,see if the coolant drops in res. if so repeat process untill coolant stops droping ,then drive car regularly if overheating stops ,but monitor it because it will drop somemore/there has been reports of new and rebuilt water pumps nt having correct propelar mounted on them/ backwards etc. if this helps let me know [email protected]

Looking at a wiring diagram I see two relay's that control the cooling fans (has two ) High speed cooling fan relay , low speed cooling fan relay . Both relays are controlled by the PCM - engine computer . Your best bet , have it checked for DTC'S - diagnostic trouble codes . Could have control circuit problems .There are videos on youtube test relay controlled circuits . How to test at the relay base (where relay plugs into ) Test power an grounds an control . Do you know how the cooling fans work ? Coolant temp. sensor inputs temp to PCM . When coolant temp reach's 200 to 220 , the PCM will energize the relay's low speed then high if temp fails to come down . Can check this data on a good scan tool . Can even turn the fans on with a good scan tool .