Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Read Codes and Reset SES light on 2001 Saturn SL-1

My “Service Engine Soon” light is on and the Saturn shop says it’s the Coolant Sensor. Some GM cars had the ability to turn the ignition key on and off in a pattern to read the engine codes AND you could reset the SES light to off. Can I do this with my 2001 Saturn SL-1?

If there is a bad sensor or bad condition, getting the light off won’t last long. Why not fix the issue? In a 2001, I wouldn’t be surprised at a faulty sensor - replace it

You are of course correct, and I plan to have the sensor replaced. However, I was discussing this with a co-worker and he mentioned the ability to reset the car light (which would be useful if you’d done the required work yourself and now needed to reset the light.) I am merely curious as to whether I can read the codes this way, and whether the reset works this way if I ever have someone do the work who doesn’t have the ability to reset the light in the normal way.

Just an update–a co-worker with a code reader brought it in today and the only code that came up when he checked my car was P0341 “camshaft sensor A bank 1 ckt 2 range perf”. This he thought might be related to the new plugs I had installed yesterday, as in perhaps the plug wires were too close to (something). When I left work at 5 the SES light was gone. I drove it to a Pep Boys where they read the computer and found no errors, only a “historical” one for the P0341. The light has been off the rest of the evening. Is this error in any way possibly related to a coolant sensor problem? I drive the car 8 freeway hours to visit relatives on a frequent basis (4 there and 4 back). I’m concerned about not getting the sensor replaced, but no one is now getting the error that Saturn claimed was the reason the SES light came on to begin with. I’m just looking for some sensible advice about this situation.

Many codes will clear themselves if the condition that caused them is not seen for a while – typically X number of starts. The number varies from car computer to car computer. That’s probably what happened here. The error may or may not come back.

You can buy a code reader for $60-$80 that you can keep in the glove box. Test it in order to make sure that you know how to use it before you need it. Starting the car a couple of times with the gas cap loose should produce a harmless error code that you can use for testing.

The one concern I would have is whether the temperature gauge on your dash panel is driven from that temperature sensor. Driving around with a potentially faulty temperature gauge would make me nervous.

(Many Chrysler models allow you to read out simplified codes by playing with the ignition key. I wasn’t aware that GM also did that, but it is possible.)

“My “Service Engine Soon” light is on and the Saturn shop says it’s the Coolant Sensor.”

Be careful of that shop. No code says it’s a coolant sensor. That code may say it is seeing an unexpected reading from that area. Further diagnostics need to be done to determine the cause. It may often be the sensor, but it is not good to rule out other possibilities without checking.

You echo my main concern–that even though the engine itself has no problem, if the sensor is faulty, it may give bogus information/instructions to the cooling system that cause an overheat. I would love to know if the temperature gauge on my dash panel is driven by that sensor, if it is a separate sensor.

In another post on this forum, I found a post by another Saturn owner that stated there are two lights that can come on to notify me about problems: the Service Engine Soon as well as the traditional Check Engine, and that the SES light may only indicate that my car is coming up on its due date for some scheduled maintenance.

If anyone knows for sure about these, any info would be much appreciated.

From what I can see on your wiring diagrams, your coolant sensor (there is only one) goes straight into the PCM (computer). The are two big plugs on your PCM. One for all the input signals. One for all the output signals. Inside the PCM a lot of magic stuff happens, there are many algrithoms and other stuff I don’t understand, but the computer is smart enough to decide what signal to send to your temp indicator on your dash, it also sends signals to turn on and off your cooling fan, a signal to control your emissions to increase or decrease the pulse width on your injectors (how long their open), and probably a dozen or so other things that are dependant on your engine tempature. BTW, you can probably reset your CEL or SES light by disconnecting a battery lead for a minute or two.

i would make sure you get the code for the service engine soon light. this topic has been covered a lot, as this is a common problem for the saturn sl. If the code is a P0128, this should help you out Service Engine Soon Light On 00 Saturn SL