P0116 Code - Corolland: the Toyota Corolla Forums

I'm hoping you all can help.

I have a 2006 Corolla 2006, 1ZZ-FE engine, with 85000 miles. I've never had an issue other than new brakes with this car.

Yesterday I got a P0116 code after a rough start. The fluid is full and the car's gauge has never gone above the middle. After driving 30 miles the code hasn't returned and the gauge has stayed in the middle after warming up.

Some background.

I was told my starter was going bad last week and I replaced it. I was also told afterwards that my battery was bad and I should change it my next visit. Since the starter was changed my starts improved but were getting worse. I also found out the mechanic didn't run a test on the battery or starter before replacing the starter and though I paid for a new Toyota Starter nothing on my paper work says Toyota only " 1 New Starter". So I'm having some trust issues.

I went to Costco and bought a battery for my brother to install. When I started the car in the parking lot the check engine light came on and after driving it about 4 miles it stalled one time. I went back to the mechanic that afternoon. He did a quick scan only and said it was a P0116 engine coolant temp sensor. He said I needed to replace that sensor tomorrow and he cleared the code. No other diagnostics were performed or event data looked at.

I left and was on my way to my brother's to get the battery replaced when the vehicle stalled twice and would only start with a battery jumps. I pulled into Walmart and they changed out the battery. They tested the battery, starter and alternator and said they were all now good and that my coolant was low.

My brother checked the coolant. He couldn't add any pink coolant because it was full. We waited till the car was cold and it was still full. After driving about 35 miles on the freeway the check engine light hasn't returned and the gauge has stayed in the middle after warming up.

Has anyone else had this problem and what do you recommend, take a wait and see attitude or take it in for diagnostics even though the code was erased and there are no symptoms?

Thanks your help.

P0116 can also be caused by electrical issues - since you have the battery and starter replaced, this would be one possible area to inspect.

Coolant should be checked via the overflow tank - don't try and open the radiator cap, as that will always look full - sometimes will overflow out. Ideally, the overflow tank should be in the middle of the "high/low" marks - as the cooling system heats and cools, it will automatically expel or draw in additional coolant as necessary.

ECT sensor "could" be going bad - so relying on the temperature gauge will not work. Readings you have might be all bogus.

I find it odd that the starter started out well, then degraded. Eventually causing the car to stall and needing a jump to restart. That to me, points to an improperly installed starter. There should be a specific amount of freeplay between the starter bendix and flywheel/flexplate - if that is too tight, the starter can drag and/or be hard to restart.

Quick question - why do you think or what caused you to believe the original starter was bad?

At this point - I'd take it into a dealership and have them double check the starter install and test out the charging system. Diagnostics, or lack of diagnostics at the first shop makes them automatically suspect of swapping unnecessary parts. Second shop was better - but be nice to get a second opinion.

If the car checks out OK - then I'd just drive it around normally and see if the code comes back, if the car starts to stall again/be hard to restart.

Thanks for your help Fishexpo101. THe code was set after the starter was replaced but before the battery was replaced, and the code was erased before the battery was replaced. THe code has not returned.

Yesterday I did check the coolant again and saw that the recovery tank was close to the minimum line. I went to the dealer and bought the 50/50 pink coolant and filled it to just above the middle of the min/max lines.

I' drove the vehicle 50 miles yesterday on highway and surface streets. The code hasn't returned and the gauge on the dash acts normal always going up to the middle or just below.

After the battery change it starts quicker now. As towhy the old starter went bad. A few days before I brought the vehicle in,the car was having hard starts. You could hear it crank for a bit then click then start, or there would be long dragging starts. I took it to my mechanic, they had me start it several times and said it was the starter. Afterwards they said the battery was going bad but I could change it the next visit.I had asked them to check the fluids and when I picked up the car they said they hadn't but I could come in again and get them checked. I've really lost my trust in them with this last visit.

I'd love to have the dealership check it out but money is a bit tight for the next two months. One question...since the mechanic cleared and erased the code, there is no event data when the code was set. Would the dealership be able to test the ECT sensor or would they also need the event data?

THanks again for your help. I really appreciate it.

They would set the ECM in a diagnostic mode and test the ECT directly. Possible you have an intermittent fault with the ECT - the 8th and 9th generation of this car is very sensitive to electrical noise.

As for the starter behavior - that doesn't sound like a bad starter to me - sounds more like bad starter contacts / weakened electricals. Also, the generations with the 1ZZ-FE and newer engines use a returnless fuel system - so they will crank a lot longer than some people are used to. Dragging bendix (starter overrun) is a known issue on the 9th gen Corolla - usually, the starter is fine, just have to check the clearances between the bendix (geared portion of the starter) and the flexplate/flywheel. If the clearance is too tight - the starter could be damaged over time.

Sorry to hear that you got the run around. Wth many cars like these - usually, you have to do diagnostics when a code pops up. Only rarely does a OBD-II point to the exact culprit. If the shop just plugs in a scanner, comes back with a code and says XX part is bad, without doing any further diagnostics - they are really doing you an injustice. Codes only indicate that a certain threshold of condition was triggered - technician has to still diagnose the condition to find out what the true culprit is.

At this point - I'd just keep an eye on the coolant recovery tank - make sure the coolant doesn't continue to drop. Wait and see if the code comes back.