"Check" Maintenance Light on from loose fuel cap?

hunterwalk · 04-02-2005, 08:46 PM

My 2005 Prius has ~800 miles and the "check" maintenace light recently went on shortly after i refilled the gas tank. Called my dealer service department who said to first check that the gas cap was on tight (it wasn't) and that this sometimes happens - it should turn off within six normal driving sessions.

anyone else have something like this occur?

Frank Hudon · 04-02-2005, 08:49 PM

yes, well know feature of your new car.

rick57 · 04-04-2005, 12:29 PM

If the system sees 3 warm-up cycles without a problem,the light will go out. The Evap ( fuel vapors) system only starts its monitor for faults when the vehicle is first started ( cold air temp/ coolant temp and within 13 deg F of each other). It then has a drive cycle it watches. But if you drive 1 mile to the store,shut it off, then drive 2 more miles to work every day, the cycle may not complete. So sometimes it may be weeks before it sees a problem. It also takes 2 trips of seeing a problem before turning on the light. When it sees the problem the 1st time,it sets the Trouble code in memory but will not turn on the light till it sees it happen a 2nd time.

DanMan32 · 04-04-2005, 03:09 PM

Rick, would the DTC reset once the cap is properly replaced ad the warmup conditions are met?

rick57 · 04-04-2005, 05:21 PM

Quote:

Rick, would the DTC reset once the cap is properly replaced ad the warmup conditions are met?

It would take 40 cycles to erase the code from the Current Code menu if it never saw a problem again. But it will stay stored in the History Codes until cleared of all data in the memory. So if you just make sure to keep the gas cap tight it should be no problem as far as that code is concerned,but if the light came back on you wouldn't know what system set it off.

So I would say just have it checked for codes when the light comes on, at least you will not have to wonder what caused it.And as a side note,there is also a Pending Code menu for storing the 1st trip of a 2 trip code.

DanMan32 · 04-05-2005, 03:38 PM

Only problem is, many dealers would charge you to discover this code and to clear it.

prius mdt · 04-06-2005, 08:30 PM

Ask Ask Ask Ask Ask ... we (at our dealership) usually give a "complementary" code clear for new car buyers (bought from us) when they are up front, knowing they left the gas cap loose. After a "this one is free, the next one will cost you" most customers are well pleased and remember to tighten until it clicks. - Maybe your dealership will do the same? - Here's an angle to try - "I know I left my gas cap loose, I don't want any system diagnostics. If I bring my car by, will you please clear the evap codes?" Ask Ask Ask Ask Ask

04-02-2005, 08:46 PM	#1
hunterwalk Join Date: Apr 2005 Posts: 1 My Car: Model: Package: Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	"Check" Maintenance Light on from loose fuel cap? My 2005 Prius has ~800 miles and the "check" maintenace light recently went on shortly after i refilled the gas tank. Called my dealer service department who said to first check that the gas cap was on tight (it wasn't) and that this sometimes happens - it should turn off within six normal driving sessions. anyone else have something like this occur?

04-04-2005, 12:29 PM	#3
rick57 Senior Member Join Date: Feb 2005 Location: Circleville, Ohio Posts: 565 My Car: Other Non-Hybrid Model: Package: N/A Thanks: 0 Thanked 0 Times in 0 Posts Friends: 1	Re: "Check" Maintenance Light on from loose fuel c If the system sees 3 warm-up cycles without a problem,the light will go out. The Evap ( fuel vapors) system only starts its monitor for faults when the vehicle is first started ( cold air temp/ coolant temp and within 13 deg F of each other). It then has a drive cycle it watches. But if you drive 1 mile to the store,shut it off, then drive 2 more miles to work every day, the cycle may not complete. So sometimes it may be weeks before it sees a problem. It also takes 2 trips of seeing a problem before turning on the light. When it sees the problem the 1st time,it sets the Trouble code in memory but will not turn on the light till it sees it happen a 2nd time. __________________ Rick Angles Toyota Master Diagnostic Technician Toyota Hybrid Technician Germain Toyota Columbus, Ohio

04-06-2005, 08:30 PM	#7
prius mdt Join Date: Mar 2005 Location: Richmond VA Posts: 25 My Car: Model: Package: Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	Re: "Check" Maintenance Light on from loose fuel c Ask Ask Ask Ask Ask ... we (at our dealership) usually give a "complementary" code clear for new car buyers (bought from us) when they are up front, knowing they left the gas cap loose. After a "this one is free, the next one will cost you" most customers are well pleased and remember to tighten until it clicks. - Maybe your dealership will do the same? - Here's an angle to try - "I know I left my gas cap loose, I don't want any system diagnostics. If I bring my car by, will you please clear the evap codes?" Ask Ask Ask Ask Ask __________________ Don - Toyota Master Diagnostic Technician

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04-02-2005, 08:49 PM	#2
Frank Hudon Senior Member Join Date: Jan 2004 Posts: 4,144 My Car: Model: Package: Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	yes, well know feature of your new car.

04-04-2005, 03:09 PM	#4
DanMan32 Join Date: Aug 2004 Location: Tampa Bay, FL Posts: 3,775 My Car: Model: Package: Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	Rick, would the DTC reset once the cap is properly replaced ad the warmup conditions are met?

04-05-2005, 03:38 PM	#6
DanMan32 Join Date: Aug 2004 Location: Tampa Bay, FL Posts: 3,775 My Car: Model: Package: Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	Only problem is, many dealers would charge you to discover this code and to clear it.