Should Mike cut the blue wire?


On this week’s show, we heard from Mike from Pasadena, with his’97 Subie. He’s looking to turn off that pesky check engine light, which is glowing thanks to an errant gas tank sensor.

Of course, he could just replace the sensor. But, that’ll cost money. So, Mike wants to know if he can just snip a wire and de-activate it. Tom and Ray thought he should stop being a cheapskate and spring for the repairs, but what do you think? Has your Subaru done this, and did you find the magic blue wire? And thanks.


Subaru’s are notorious for faulty check engine light activation. Usually, there is nothing wrong with the car. The factory is aware of this problem and will reboot your computer to stop the false alerts. Note: This is not merely clearing the code! They must reset the computer itself to fix the problem.

Good luck!


Mike, I’ve had a similar problem with my 2000 Outback. The engine light has been coming on regularly for more than three years and 80,000 miles. Initially I was told it was the 02 sensors. I had those replaced, and the light came back a month or so later. I then paid a bunch to have the catalytic converter cleaned, or washed or something, and the light still returned. So, now with 162,000 miles, and the light still returning, I’ve ignored it for the last three years. A friend with a 2002 Outback has had the same problem as I have, but he was smart enough to pay next to nothing in repairs (and thus has $1000 or so more in his savings account than I have). He also continues to ignore the light.


Man, don’t snip the wire. Geez. What kind of cheapskate…

Remove the bulb. :slight_smile:


My wife had this problem with her 2001 Forester. I had the gas cap replaced with a locking gas cap, which fits more snugly and the problem has disappeared.


Mike, go here: register and be amazed. BTW, a loose gas cap IS the most common CEL thrower on Subies.

Unless you have problems with annual inspections that preclude the obvious solution (black tape) ignore it. Since I live in Montana, I ignored our 2000 Legaback CELs for years, and am currently ignoring a six-month CEL on the Barbie Jeep (Tracker). The 2006 Outback hasn’t thrown on yet, but when it does, I will ignore it also.

I too obsessed about not knowing if there was something dreadfu going on, until I learned that these CELs are all about satisfying Congress.


Don’t cut the wire…! The errant sensor probably closes the circuit when it works, so by cutting the wire, you’d only be opening it permanently.

I like mr_josh’s idea of removing the bulb as a stopgap measure (so simple that it’s brilliant!)

If the other contributors are correct in pointing toward a poorly sealed gas cap, you may be able to pry out a few bucks for the gas cap, and still preserve your reputation as a cheapskate.


The CEL comes on solid to warn of emissions related problems. Many systems will FLASH the CEL to warn of immediate driveability problems that can result in severe engine damage (e.g. persistent misfire). You may not even be aware that the serious problem exists without the light. Then again, they say ignorance is bliss…


I can’t believe how many people think disabling the check engine light is a solution! That light is NOT the problem. The problem is something else and should be fixed. Even if the light is a false alarm, then that should be fixed because the light should be there to tell you when something else goes wrong. This is like having the dipstick break off and just not checking your oil any more because the dipstick isn’t long enough. NO! Fix the problem, don’t ignore it.

Of course, I just recently spent $4000 to replace an engine because I convinced myself that a warning light was a false alarm . . .


Suggest Mike ensure the code thrown the engine management system is correct. If so, then if he has ready acess to this “blue wire” cut it and see if the CEL is extinguished. If so, great: if not, then reconnect the blue wire and find out what’s wrong. Most certainly something else is wrong with the engine or emission system. In any case, he’ll have to get it fixed to register the car in CA.


On my '99 Outback, I had the CEL light on, and indeed, when it started to misfire the CEL flashed. I thought it was just a second code, but your suggestion makes more sense. ‘Rebooting’ the car fixed the misfire problem, and hasn’t come back since.


…and put the bulb up on EBay.


Control electronics that are monitoring feedback sensors are looking for readings that make sense to them. A range of valid resistance/voltage readings or a number of cross counts over time are a couple examples. An open circuit doesn’t count as a good feedback signal and so will do little to extinguish the CEL.


Check engine light on and off all the time. Have performed all recommended maintenance. Had O2 sensor replaced, it was faulty, dealer put in another. Now stuck with same problem. On and off, on and off. I am so tired of this! Go to auto repair shops and they say possibly need new gas cap, fuel injector, O2 censor, knock sensor, possible vapor leak, catalytic converter. My car has 132,000 miles so I can’t get emissions stuff done under warranty. What the hell is going on with check engine lights in Foresters? I can’t get my vehicle inspection approved with the check engine light on. I have MS & support a family so like most of us don’t have tons of money to spend on a car I have taken very good care of. Can the dealer reset the light long enough for me to get an inspection sticker until I have enough money for repairs? And how do I know for sure exactly what repairs are necessary or not? I’m no mechanic, I’m a nurse.


Take the car to an Autozone, if you have one nearby, or some other big car parts store. Autozone will read the codes from your computer for free, other places may also. Get the codes, the actual codes not the description. The codes will be something like P0303. There may be more than one. Write them all down and post them back here. The codes should help us narrow down the possibilities. The range of possible problems you list tells me those folks aren’t reading the codes and are just guessing, or you have a lot of codes set.

You should probably do this in a new thread in the Car Questions section.


A piece of electrical tape will cover the light and after turning the radio up as loud as it will go, Mike should be able to motor on worry-free.

Better yet, why not use a long strip of tape and cover ALL of the warning indicator lights. Why put up with a stinkin’ irritant like a CEL, alternator, high beam indicator, park brake, or oil lamp light.
Unplug the dash gauge temp sensor and then he won’t even have to worry about overheating anymore.


Hey, its Mike! It seems the comments have gone a little off-track. I have a CEL that routinely comes on, stays on for awhile, then goes out again. I know it is caused by a faulty gas level sensor in my gas tank. This is the problem that always kicks out a code to the computer. What I want is to kill that particular CEL warning so that if the light does come on I can assume its a different problem.

I am only sort of a cheapskate, in that replacing the sensor in the tank costs hundreds of dollars. And, having it not work is no big deal (I watch the odometer for when to fuel up), it just causes the once-in-awhile CEL that annoys me. And once in awhile I can watch the gas gauge just drop from way up to way down, like its spilling out the bottom of the car.

Thanks for all the input! I think I will go on ignoring it. Soon I will be replacing the car (I hope) as my wife can’t drive the manual tranny, and its a pain having to switch cars in the driveway and moving my son’s car seat around.


If you know for certain this is the problem, and I wonder why the fuel level sensor would even trip the CEL, then you could put a resistor into the circuit replacing the fuel sending unit. It would make the gauge permanently read part way up the scale (exactly where would depend on the resistance value) but this should cure the CEL. Now, is there a plug somewhere that would keep you from having to cut any wires?


The problem with de-activating the light is that it will then be deactivated (same problem as leaving it stay on and not fix the problem). If that light does not work, then the owner will not know when some other problems come along and they could be far more serious.


When the check engine light comes on, it does NOT mean the sensor is bad. The sensors do two things: they SENSE and they report back to headquarters (the engine computer) which then tells you, via the check engine light, “Hey, our boy Sensor is reporting something is wrong with Component/System. Hook me up with Scan Tool and I’ll give you more details!”. Sure, Sensor CAN be overly sensitive, or less often, just plain wrong; but, you need to heard what he has to say before you cut him off. His warning might save you from those dread ogres, Major Malfunction, and Major Expense.