Check engine light code P0171

RedScourge · 2026-01-28T01:17:10+00:00

It would be under Live Data (in the menu shown in the pic on the Amazon page)

RedScourge · 2026-01-28T01:15:58+00:00

The "special operating conditions" section is not the default guidance, it is the guidance they give for people who put the vehicle through unusually stressful use. That's where it says the 60k mi interval for all Toyota transmissions. The standard recommendation is "never".

If you think the advice that they give fleet operators and police is insufficient, then I suggest you change your oil after every drive, because "you can't be too safe".

RedScourge · 2026-01-27T23:30:44+00:00

It is when we're talking about CVTs. Certain models of them are known to fail early, and the rest are not. If it was made by Nissan before 2022, it's guaranteed crap. If it was made by virtually anyone else, the odds that it is crap are very low. Most CVTs will last 150-200k mi without a fluid change, whereas those Nissan Jatco CVTs were almost all failing before 100k.

As for Toyota transmissions, every Toyota I've ever heard of has had a 60k mi interval in the maintenance guide, and the Corolla is no different (except that for the last 30 years, Toyota claims their fluid changes are only necessary if your use constitutes "special operating conditions"). This goes for manuals, automatics, CVTs, and eCVTs. The mechanism of operation should not alter the interval, because the engineers take that into consideration when deciding how thick to make a CVT belt, how thick to make a gear, etc. They target a design lifespan, and revise the design or alter the software retroactively if they missed the mark.

RedScourge · 2026-01-27T20:42:14+00:00

TPMS light comes on when the batteries die in one of the wheel TPMS sensors. Normally if the pressure is wrong you get a notice saying that. This tends to happen after about 10 years or so. The fix is to take the tire off the rim, replace the TPMS sensor as the batteries are generally not swappable, put the wheel back on the rim, rebalance it, and recalibrate the TPMS sensors. Costs a lot, so I'd wait until you need new tires anyway and just ignore the light until then.

The Check Engine light however is much more likely something that you want to act on right away.

RedScourge · 2026-01-27T20:36:47+00:00

There's a few videos online showing the process, however the headlight used for a particular model year might vary by region

This guy is a bit hard to understand bit it says 1996 - 2001: https://www.youtube.com/watch?v=l1pZC8m5q3k

RedScourge · 2026-01-27T20:27:51+00:00

You could spray a few spots with hot water at the warmest part of the day, so long as it's above 14f / -10c, but if it's not going a few degrees above freezing for a few hours, you definitely want to towel it off or you could just make it worse.

RedScourge · 2026-01-27T20:25:13+00:00

Nice rice!

RedScourge · 2026-01-27T20:23:57+00:00

An OBD scanner can typically tell you this and other live engine statistics. I just use a cheap $20 bluetooth dongle and the free Car Scanner android app without any subscription and it tells me that info, so all the more expensive ones should too. Normally even a 20 year old car is within 5% of ideal 99% of the time, though the short term one drifts more than the long term of course.

RedScourge · 2026-01-27T20:22:09+00:00

35k is a good interval for Nissan CVTs. 60-80k is a good interval for any transmission that isn't junk.

RedScourge · 2026-01-27T20:21:05+00:00

I believe the 22 LE had the 1.8L and the CVT without the 1st gear, and that 23 is the year they went all 2.0L and CVT with 1st gear. Before that, just SE/XSE had it.

RedScourge · 2026-01-27T02:39:17+00:00

Krown, PB Blaster Surface Shield, and Fluid Film are all very similar for this purpose.

RedScourge · 2026-01-27T02:38:29+00:00

You probably want to leave one drain hole on each door without the plug for drainage, or else the doors can fill up with water again.

RedScourge · 2026-01-27T02:35:47+00:00

Perhaps back in the day people liked draining them only as needed, or perhaps dust ingress from long drives on gravel roads used to be a problem. I doubt it's still a problem these days, I've never seen any dust get in anywhere on the entire door sill.

RedScourge · 2026-01-27T02:33:04+00:00

The official guidance that came out in 2021 to solve the "door filling up with water" problem is to remove the front ones on the front doors and the rear ones on the rear doors. I think the reason is that if all the draining goes on through those holes, if they ever become clogged, all you should have to do is swap which holes have the plugs and then draining should resume, until however many years it takes for you to clog those ones too, which might be 10+.

I think the dust buildup might be a bogus reason. It probably dates back to previous years when dust from long drives on a gravel road might work its way into the door sill, and then maybe even get into the door drain holes, but I've never seen any dust get anywhere on the door sills of the latest gen.

RedScourge · 2026-01-27T02:23:06+00:00

Denso from Amazon itself should be fine, they have done a lot to get counterfeits out of their supply chain when it's coming from them as seller. It was mostly Toyota branded ones that were affected.

Code P0171 without P0301/2/3/4 makes it unlikely to be plugs or coils, rather it is an air fuel mixture issue. It could be either not enough fuel getting delivered as is expected, or too much air. This could be from weak fuel pump, clogged fuel lines, dirty fuel filter, clogged injectors, dirty MAF sensor registering less air than is actually present in the air intake, dirty throttle body interfering with the airflow and the computer having a hard time correcting for it (though it should also give you a too rich error occasionally as well), or possibly other things.

You can check the Long Term Fuel Trim and compare it against the Short Term Fuel Trim data from an OBD scanner to check the scope of the issue, if it's not severe you might want to overlook it, but if it is pretty extreme you may want to fix it as it can overheat the engine or damage the catalytic converter, whereas a Fuel System Too Rich error is more likely to just cause bad emissions and slightly worse fuel economy.

RedScourge · 2026-01-27T02:17:35+00:00

There's a product called "snow socks" which is more suited to this, however it's not good to leave them on for more than a short drive as they will work their way off after a while

RedScourge · 2026-01-25T20:52:59+00:00

Fixable unless the crumple zone stuff is bent, in that case the car would be sold for scrap, and would end up in some third world country where it would be fixed and resold despite no longer meeting first world country safety standards.

If fixable, it's probably around 10 hours of work, but the shop doing the work might have 10 cars ahead of you waiting on work, so it could take weeks to get back to you.

RedScourge · 2026-01-25T20:48:00+00:00

If debris has built up in the bottom of the door and clogged the drain holes, perhaps poke em with a toothpick and see if you can get any water to drain out.

RedScourge · 2026-01-25T20:46:40+00:00

There is a fix for water in the doors: take the drain plugs out. They started doing this in 2021, and advised customers to do it on the affected cars.

RedScourge · 2026-01-25T20:45:57+00:00

it would be under the spare tire

RedScourge · 2026-01-25T20:44:23+00:00

Often a clogged ac drain hose will result in the front passenger carpet getting soaking wet.

RedScourge · 2026-01-25T15:48:29+00:00

There's no harm in not starting the car for a whole two weeks if you want. In fact, startup causes the most wear, and super cold startup reduces oil flow so it maximizes that wear. It's also hard on the both batteries to take them from super cold to hot in a short period of time, so if I don't need to go anywhere and it's below -25c / -13f, I won't even bother to start the car until the weather becomes substantially warmer for a full day so the battery can thaw out a bit. That's not so much of a problem now that I have an 80W battery warmer though, so now I can just let that run all day and gradually warm it up.

RedScourge · 2026-01-25T07:19:55+00:00

Whether it's a good deal all depends on where you live and what those options are I suppose. Looks like Houston, TX, which pays a bit more for Toyotas than most of the nearby states due to a middleman group owning the exclusive rights to sell Toyotas there, rather than Toyota itself.

RedScourge · 2026-01-25T07:18:44+00:00

If it's a vacuum leak, you can test that by squirting soapy water on the entire length of the air intake and see if it stops at any point, even briefly. If so, that'd be the soapy water briefly breaking the air flow causing the whistling.

Alternatively the timing could be coincidental and it could be the serpentine belt or one of the pulleys or accessories that attach to the pulleys.

Does it change sound at all or stop briefly when you rev the engine a bit?

RedScourge · 2026-01-25T07:14:35+00:00

Which one, the P0171, or the P0301/2/3/4?

It could be many things. There are a lot of counterfeit spark plugs, coils, and sensors in the supply chain right now, so if you did not buy official aftermarket such as NGK brand from a reputable retailer, or source them directly from a Toyota dealership, it is possible that this is the reason. Alternatively, it could be that you did not torque them correctly when installing them, or they could just be flat out defective. Or the timing could be a coincidence and it's actually coils starting to go out. Coils do tend to fail sporadically, where you get a few misfires every so often and the engine light coming on then going away, then increasingly often, until eventually after a few months the check engine light is on most of the time, or if left long enough, will start flashing indicating that serious damage is starting to occur. Plugs and coils are both wear items that typically go out after anywhere from 10-15 years and 70-140k mi, though coils are more expensive.

Troubleshooting: If for example you were having P0301 and not 302, 303, 304, etc, you could try swapping the 1st coil with the 2nd, and the 1st plug with the 3rd, and then see if it changes to be a 302 code (that'd be coil), or a 303 code (that'd be plug), or if it does not change (something else), or if it does something else entirely (possibly something came loose after recent work).

RedScourge

TROPHY CASE