My 05 Toy Tundra has been a joy for 90,000 miles. This is the only real problem:
Thinking the seal on the gas cap was causing the check engine light to come on, I cleaned the rubber cap seal and the metal receiver with Armor-All.
After a few start-stop cycles, the light went out, so I bought a new cap.
A couple months later, the light returns.
A squirt of Armor-All and 3 start stop cycles and it goes out for 150 or 200 miles.
It seems too unlikely to be true. What could it be?
The gas cap is often a good place to start, but…there are lots and lots and lots of things that can cause this, and there is no way to just guess about it. The next time it comes on pull into an auto parts store (big chains work best) and ask them if they can read your computer codes (diagnostic trouble codes / DTCs) and then post them (the actual codes, like P0123 - not what anyone says about them). This gives folks a place to start.
If the light ever starts blinking at you get off the road and shut it down ASAP - like on the shoulder, not even at the next exit or turn off. If the light continues to blink you should have it towed as you can cause real damage. If it is just on solid & comes & goes you can continue to drive but do need to get it diagnosed.
First step is to find out for sure what is triggering the light. That means getting the error code checked. Post it back here. It should be in the form P0123.
I would not want Armor-All anywhere near my car, but that is your choice. If the cap is not making a good seal Armor-All will not fix it. If the code turns out to be as expected then replace the cap, they are only a few dollars.
BTW many auto part stores will read those codes for free.Some vehicles simply don’t have a lot of margin between working perfectly and setting an error code. And I suspect that the code in the ECU computers is not always error free. Our 1995 Neon used to set error codes for one or both O2 sensors every three or four months – even when the sensors had been recently replaced.
Best bet is probably to buy a cheap code scanner. There are several at amazon.com for a bit less than $40. You’ll probably have to spend $60 at a local parts store. Once you have the code(s), you can look it up on the Internet. Be aware that the code descriptions have more to do with where the fault is detected than what is causing it. With Google to help, you can determine if the code is serious, what might be provoking the code, whether other drivers of your car and model have similar problems, and what they do about them.
Our 1995 Neon used to set error codes for one or both O2 sensors every three or four months – even when the sensors had been recently replaced.
The error codes don’t say replace the sensors. Really they don’t. Why would they put a sensor in the car who’s only job was to report if it was working properly?
Those sensors trigger an error when there is a problem with the gasses they are measuring. The usual failure mode will also trigger an error. Why does everyone want to assume it is the sensor? OK often it is just the sensor, but it should be checked. Don't shoot the messenger.BTW many auto part stores will read those codes for free
Around here, the place that advertises free code check also proudly claims only half their customers need major trans repairs. Fifty percent odds they will try to cheat you or do you feel lucky?
The gas cap was probably at the limit of my tech skill. It was fairly cheap, and the light went our for several thousand miles.
While these responses have an intelligent quality about them, what was hoped for was something like “Oh, mine did that and…”
***The error codes don’t say replace the sensors. Really they don’t. Why would they put a sensor in the car who’s only job was to report if it was working properly? ***
I beg to differ. If you look at the O2 related error codes, they really do say ‘replace the sensor.’ I wouldn’t necessarily rush right out and do that, but not for the reason you wouldn’t.
The O2 sensors are not intended to be problem detection devices. They are intended to report the data needed to properly control the fuel/air mixture. Their readings can be used to detect some types of engine malfunction. And the ECU will presumably will detect and report those conditions. But it shouldn’t call them O2 sensor errors. Maybe an exhaust stream really rich in Oxygen (or some other reactive gas?) might trigger an High voltage O2 sensor error. But things like the ever popular P0134/P0140 (“Sensor circuit no activity detected”) almost certainly are due to either a bad sensor, bad wiring, or ECU bugs. For a 1995 Neon, any of the three is a reasonable hypothesis.
I think there are a number of sensors that will routinely get blamed for problems elsewhere. I’m sure that I’ve encountered them. More than once. But I’m blanking on an example. I just think that O2 sensors aren’t normally in that class.
Around here, the place that advertises free code check also proudly claims only half their customers need major trans repairs. Fifty percent odds they will try to cheat you or do you feel lucky?
I have used auto part stores three times for reading codes. Not once did they even suggest buying a part, much less recommending service. They read the code, gave me a little print out of the codes and I thanked them. Now I have my own code reader, but I still go to those two auto part stores for any auto type things I need.
The engine computer doesn’t/can’t check some things every time the vehicle is driven. For the EVAP (fuel evaporation control system) sensors and circuits, it might be several vehicle trips before the required conditions are present that the engine computer is allowed to check those sensors and systems. For example, the gas tank has to be at a level of 1/4 to 3/4 filled before it can, say, check the seal of the gas cap. So, you might drive 100 or 200 miles before a check gets done. Then, if a problem is found, the check engine light gets turned on, and a trouble code gets set in the engine computer.