Q: Check Engine Light on again after thermostat replacement.

asked by on January 25, 2016

I got my car serviced about a week ago for a thermostat problem. The issue was fixed, but I was going to take my car in for a smog check and the check engine light came on again. The light hadn't been on for a few days after the fix. I took the car in to the smog check and the technician ran a diagnostic test. His reader indicated it was a thermostat problem. I just want to know why the check engine light came back on after the thermostat was already replaced.

Check Engine Light is on Inspection $79.99 - $89.99 Get a Quote

If the check engine light is coming on and a code like P1217 is in the computer then the computer is seeing an overheat conditions from the coolant sensor telling it your engine is overheating. This can be caused by a defective coolant sensor, radiator partly clogged, fans not working, thermostat or internal engine head problems. The system should be checked with an infrared temperature probe to see if the temperature of the engine is close to that the computer is seeing from the coolant sensor. If the coolant temperature sensor input to the computer is within about ten degrees of what the infrared tested is reading on the outside of the sensor then this would be okay. The problem may be somewhere else in the system and would need further diagnostics to check if other components are working properly. The fans will need to be working along with the water pump pumping coolant through the radiator and the radiator cooling the engine as designed. I recommend having the vehicle inspected by a certified mechanic to diagnose your Check Engine light and come up with any repairs needed.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

What others are asking

My brakes don't smoothly stop when applied. What's causing the inconsistent pressure?

The choppy sensation you are feeling when applying the brakes is most likely unevenly worn brake pads and/or rotors. When brakes are applied heavily or held for extended periods of time, this can generate an enormous amount of heat. As...

My temperature gauge reads cold - 2004 Chrysler Sebring

Hello there. A few common faults will cause your 2004 Chrysler Sebring to to stay at C on the temperature gauge. The most common are a faulty coolant temperature sensor, failing temperature gauge, or wiring harness fault. If the engine...

Engine dead.

Hi, you could of had one of a few different issues that could cause the stall. The first is a recall on the power train control module needing reprogrammed and it is causing stalls during warm up. The other issue...

RPMs are fluctuating during idle - 2014 Nissan Altima

Hello. The first thing to check is what problem codes are setting the Check Engine light. The throttle position sensor, a clogged fuel filter, or dirty throttle body could produce the symptoms you describe. Most auto parts stores will read...

Engine light on, black smoke coming out exhaust on acceleration and fault codes

The glow plug faults are most likely going to cause a hard start condition, which will be most noticeable when the engine is cold. The colder the engine, the more difficult it would be to start usually. Often times, glow...

AC not working.

An A/C system can be divided into 3 different sub systems. These sub systems work for the most part independent from each other. The heater part of it works off of water from your engine. The refrigerant part is what...

My check engine light came on...car isn't overheating no change in engine temp gauges..autozone used one of their testing gages sa

There are several possible reasons for a check engine light to come on. Typically, when the check engine light appears, the first step is to pull the diagnostic codes out of the computer with a scan tool, like you did....

Truck overheating coolant not cycling throughout engine. 2002 Chevrolet Silverado

Hey there, thanks for writing in. You need to make sure all the air was purged out of the cooling system. If you did not get at least 2 gallons of coolant mix in the engine, then you may have...

Is a high RPM maintained all-throughout a ride normal?

Hello. The first thing you should do now that a warning light has illuminated is to have the vehicle scanned for diagnostic troubleshooting codes. These codes will tell you what system (air, fuel, or spark) the computer is having problems...

Related articles

P0076 OBD-II Trouble Code: Intake Valve Control Solenoid Circuit Low (Bank 1)
P0076 P0076 code definition Intake Valve Control Solenoid Circuit Low (Bank 1) What the P0076 code means P0076 is an OBD2 code that indicates an issue with the Bank 1 intake valve control solenoid circuit. This tells us that the...
Symptoms of a Bad or Failing Throttle/Accelerator Pedal Position Sensor
Common signs of a faulty pedal position sensor include inconsistent engine response, reduced fuel efficiency, and the Check Engine Light coming on.
P0701 OBD-II Trouble Code: Transmission Control System Range/Performance
P0701 means a malfunction in the automatic control system has been detected. Issues may include transmission failure, overheating and engine stalling.