2001 Techstream codes- what am I looking at?

There is nothing NEW about a remanufactured/rebuilt HV battery. Rebuilders take working modules from other HV packs, ideally run 3 discharge/recharge cycles on each module, then assemble them into another pack. A "warranty," is oftentimes added to give the victim some peace of mind.

For greatest longevity/peace of mind/trouble free operation, a NEW HV Pack from Toyota is the way to go. Expensive yes. But too many horror stories from victims who buy rebuilt HV Batteries, and end up spending more than if they had gone with a NEW HV Battery from Toyota.

Is the Optima fully charged? Should be close to 13V w/ no load. Under a load, should still be above 12; however, the closer to12V a load reading gives, the battery should be changed immediately.

Is your 2001 a salvage? Were the correct NGK or Nippon Denso, Irridium spark plugs used?

These DTCs are for a Gen2 Prius; don't know if these would be identical for a Gen1.
P0172: System Too Rich (Bank 1)

Injector has leakage or blockage
Mass air flow meter
Engine coolant temperature sensor
Ignition system
Fuel pressure
gas leakage in exhaust system
Open or short in A/F sensor (bank 1 sensor 1) circuit
A/F sensor (bank 1 sensor 1)
A/F sensor heater (bank 1 sensor 1)
EFI M relay (integration relay)
ECM​

P0300: Random/Multiple Cylinder Misfire Detected

Open or short in engine wire harness
Connector connection
Vacuum hose connection
Ignition system
Injector
Fuel pressure
Mass air flow meter
Engine coolant temperature sensor
Compression pressure
Valve clearance
Valve timing
PCV hose connection
PCV hose
ECM
​

P0301: Cylinder 1 misfire detected

Same as P0300
​

P0304: Cylinder 4 misfire detected

Same as P0300​

P0420: Catalyst system efficiency below threshold (Bank1)

GAs leakage in exhaust system
A/F sensor (bank 1 sensor1)
Heated oxygen sensor (bank 1 sensor2)
Three-way catalytic converter (exhaust manifold)
​

P0440: nothing listed

P0441: Evaporative Emission Control System Incorrect Purge Flow

Fuel tank cap is incorrectly installed
Fuel tank cap is cracked or damaged
Vacuum hose is cracked, blocked, damaged, or disconnected [(1), (2), (3), (4), (5), (6), and (7) in fig 1)] Vaccum diagram needed.
Open or short in vapor pressure sensor circuit
Vapor pressure sensor
Open or short in VSV circuit for EVAP
VSV for EVAP
Open or short in VSV circuit for CCV
VSV for CCV
Open or short in VSV circuit for pressure switching valve
VSV for pressure switching valve
Fuel tank is cracked or damaged
Charcoal canister s cracked or damaged
Fuel tank over fill check valve is cracked or damaged
ECM​

P0446: Evaporative Emission Control system Vent Control Circuit

Same as DTC P0441​

C1202 (there should be subcodes (511 or 512; go back and double click C1202): Brake Fluid Level low/Open circuit in Brake Fluid Level Warning Switch Circuit

Brake fluid level
Brake fluid level warning switch
harness and connector
Skid Control ECU​

C1252 (there should be a subcode 130): Hydro-booster pump motor malfunction

Brake actuator assembly
​

C1256 (there should be a subcode 141 or 143): Accumulator Low Pressure Malfunction

Brake actuator assembly (accumulator pressure, accumulator pressure sensor, pump motor)​

 

I thought you had earlier decided to sell this car.

If you have decided to continue to work with its problems, I suggest you go back to basics and check engine compression - regarding the engine misfire issues.

This requires that you purchase an engine compression gauge with a fitting that will screw into the spark plug holes. Remove the four spark plugs, use Mini VCI and find the software command for engine compression testing so that MG1 will spin the engine at a lower than normal speed, suitable for testing purposes.

Regarding the rich air/fuel mixture, has the oxygen sensor #1 been replaced yet?

 

The misfire DTC are the first ones that need to be addressed.

I would start by checking engine compression. If it turns out the car has a problem with one or more cylinders, there is no point putting more repair $$$ into the car unless you are willing to first install a used engine.

 

Answers to the laundry list of codes provided free of charge. You're welcome.

People who know me well, appreciate my candor. It may not be what they want to hear, but its what they need to hear. If you don't appreciate candor, please add me to "People You Ignore," and I will disappear from your PriusChat world.

I don't work for Toyota. If I did, I would be telling you to get a new Prius, zero percent interest, give you a few dollars towards your Gen1. Then proceed to tell you to see Sales Mgr "John Smith," at "ABC" Toyota Dealer in "Some City", Arkansas.

You said "New Rebuilt," HV Battery w/ 70 miles. I was just correcting your view of "NEW:" it does not exist with rebuilt HV Batteries. I advocate for NEW HV Batteries for owners who plan to keep their car for some time. There are lots of horror stories of people going the rebuilt/refurbished route, only to later regret it b/c the warranty proved useless and/or the labor of removal and installation of the replacement ran super close to a NEW HV Battery, when factoring the total cost (battery + initial install labor fee + warranty installation labor fee). If multiple refurbished/rebuilt/used replacements were required, these "victims" ended up paying MORE than if they had just gotten a NEW HV Battery; these individuals learned the hard way. It is ultimately your car, money, and time, so do as you please.

Regarding prudent use of finances to repair a 2001 Prius, or any old car for that matter, make sense to me, if:
1) I am able to do the repair needed. A ton will be saved on labor costs, as it is now just time. When I replaced the front struts and rear shocks, I saved $800 (Cabe Toyota) or $1000 (Hooman Toyota) on dealer labor, by not going to these two dealership. Independent repair shops and chain repair stores were not that much cheaper either. I enjoy the auto repair challenge and it provides me with some personal satisfaction too.
2) Is the car in question in acceptable overall shape and mechanically sound, except for the current repair needed.
3) Cost of the parts needed for repair.
4) I like: not having car payments, cheap vehicle registration fees, and cheaper insurance. Sure I wouldn't mind a new car, but as long as 1, 2, and 3 make sense to me, I will buy parts and make time for the repairs. Yes, at some point, I will have to throw in the towel.
5) In the case of an HV Battery, if the current one dies after warranty, but before 220,000 miles, I would still buy a NEW HV Battery. Hopefully by that time, maybe the HV Battery pack will be under $2k. If after 220,00 miles, maybe I will rebuild a Gen3 pack myself using 3 discharge/charge cycles per module.

Since you don't DIY, you could make this a project car. Assuming you want to personally challenge yourself, have a garage, and have the funds to acquire tools, parts, etc. If you hate working on cars, probably best to get it working, if the repair costs doesn't exceed $500, to maximize the resale value. If repairs exceed $500, cut your losses and sell to a junk yard or someone who wants a project car.

 

The DTC info provided by exstudent from a Gen 2 book is mostly close, but it's most useful to use the manual that matches your car...

• P0172 (4 pages of workup) mixture too rich (or problem sensing it)
• P03xx (6 pages of workup) engine misfiring
• P0420 (3 pages of workup) catalyst efficiency (or problem sensing it)
• P0440 (6 pages of workup) evap system control malfunction
• P0441 (6 pages of workup) evap system purge flow (or problem sensing it)
• C1202 (2 pages of workup) brake fluid level (or problem sensing it)
• C1252 (7 pages of workup) brake accumulator pump runs too long
• C1256 (6 pages of workup) low accumulator pressure (or problem sensing it)

The "pages of workup" here refer to the pages found in volume 1, diagnostics, of tests and decision-tree procedures to systematically rule out possibilities until you know what actual problem you have that is causing each code to show up. They don't include repair procedures (those are in volume 2, and don't matter until you know what needs to be repaired). In other words, it's generally not the case that just having a code tells you what needs to be fixed. Having the code strongly hints you toward a set of workup steps through which you can zero in on what needs to be fixed.

I haven't tried to do a summary of the relevant 40 pages of workup here in this post, because it could easily turn out that some piece of information I chose to leave out for brevity was key in your specific situation, so it just seems like I'll be giving better advice if I just say, if you want to tackle the diagnosis of any of those issues, there's good information in the manual and you know where to find it.

Cheers,
-Chap

 

Chapman did a great summary:

I suspect the first three are a common fault, the O{2} sensor(s) but they could be due to oil fouling. If the car needs oil, frequently, an engine swap or rebuild it the only alternative as Patrick pointed out.

The two middle problems could have been induced by over-filling the tank and possibly an air leak. Over-filled tanks can soak to carbon canister and the only solution is replacement. It could also impact mixture. Do this fix first.

The brake problem can probably be resolved by driving the car around for several miles with frequent brakes. Then buy the right grade of brake fluid and top off the brake fluid tank. The braking is important to make space for the brake fluid. As the pads wear down, slowly, they draw down the fluid.

GOOD LUCK!
Bob Wilson

 

I respectfully dissent ... in my universe, never add fluid to the brake reservoir except immediately after you have:

1. parked
2. turned the key OFF
3. pumped the brake pedal until the feeling abruptly changes and it's rock-hard and barely moves (this is not a subtle change, you can't miss it - takes somewhere between 30 and 40 strokes usually for me - the manual says "more than 40" just to be safe.

NOW, and only now, you can look at the level in the reservoir and add fluid just up to the MAX line.

Now, turn the key ON (not START, just ON) and listen for the accumulator pump. By the time it stops, the reservoir level should be somewhat below MAX. That's your normal level for when the normal amount of fluid is stored in the pressure accumulator. (It will also slowly drop further from that level, as the brake pads slowly wear.)

The reason for that procedure is that in normal operation, the level should be somewhat below MAX just because a bunch of the fluid is stashed away in the accumulator (30 or 40 strokes' worth). Doing your 30 or 40 strokes with the power off returns that fluid to the reservoir so you can read the level correctly. If you top it off while fluid is hidden in the accumulator, you overfill the system.

Reference: 2001 service manual volume 2, page BR-6:

To be OCD about it, if you do this any time except when the pads are brand new, you're still adding a bit extra fluid to the system; it will come back a bit above MAX when new pads are installed (unless you're in the "crack bleed screw to push piston back in" camp). But the manual isn't OCD about it, because there's enough extra room in the reservoir for that. They just have you adjust the level back down or up to MAX in step 12 at the very end of the pad replacement procedure. If you're in the "crack bleed screw" camp, you might end up adding a bit of fluid. If you're not, you may end up syringing some back out (if any fluid was ever added) to get it back down to MAX. If the system has never leaked and never had fluid added, putting new pads in will magically put the fluid level exactly back at MAX where it was in the factory.

-Chap

Couple extra notes:

1. The steps given above work in Gen 1. Apparently in Gen 2 and later, the accumulator pump can run even with the ignition off, so you could pump forever in step 3 (or at least until the 12 V battery dies) and never feel the brakes get hard. So in those later generations, you actually have to pull relays for the pump first.
2. Because CClay has C1202 and C1252, suggesting all is not well with the pump or accumulator, it's possible the pedal might already be hard and the fluid is already in the reservoir. It's also possible after turning the key back ON, the pump will run and not stop. (By the way, CClay, do you know the sound of your accumulator pump when it's running? When it runs, how long typically before it stops?)

 

Chapman is right but I was in a hurry.

I knew the level was low because the brake light would flash on a hard turn. It had been doing this for years mostly in cool weather. But a couple of months ago, I started seeing it on straights after having tapped the brake. Yet the next morning, the level looked OK.

So on the way into work, I picked up a can of brake fluid specified in the owner's manual. I continued into work using "N" to brake and sure enough, the level was now low. I added the fluid to the fill line and tossed the sealed can in the trash into work. No more brake light events.

Chapman's technique is much better than my ad hoc. Good, fast, cheap: this was fast and cheap.

Bob Wilson

 

<embarressed>You've raised a good point. It is important to clear the codes and then drive the car to find out which codes come back. They are not time-stamped so we clear an codes found 'on the car' and then address the others.

Also, anyone who replaced a brake line should have handled 'bleeding the air' out and making sure there is enough fluid. I was sharing what I did the last time I topped off. If you are not seeing the 'brake' light, It would be right to clear the code and see what comes back.</embarressed>

A lot of things can cause vibration on a turn including worn tires, alignment, wheel bearings, a missing lug (raises hand) and even worn CVTs. Use the tire tool to make sure the lug nuts are on securely. With the car parked and the wheels turned, look and feel the inner and outer treads to see if there is unusual tire wear.

I've got to scamper into work but tread depth is measured in 1/32 inch units. The limit is 3/32 but you can also check the wear strips. These are places that wear down first and show a spot where there is no tread. Google should find plenty of examples and how to evaluate tire wear patterns.

I bought a 'life-time' alignment' service from Firestone for each Prius. I used it two weeks ago to get a steering instability fixed.

Bob Wilson

 

I'm wondering if you had an iffy seal in the system somewhere, so that overnight the accumulator pressure would drop and the fluid return to the reservoir. That would explain the level looking higher first thing in the morning. Probably, it was accompanied by a longer-than-normal pump operating sound when you first turned the key on in the morning, to shift all that fluid back into the accumulator again. (Though if it had been that way a long time, it could have sounded normal to you.)

Probably when you saw it first thing in the morning and "the level looked OK," it was sitting somewhere between MIN and MAX which normally would be OK, but if really all the accumulator contents had returned to the reservoir overnight, then those really would have been the correct conditions for checking the level, and it should have been right at MAX.

Of course, we don't know if all the accumulator contents went back or just some ... so the best way to account for those variables is to just pump the brakes with the key OFF until the assist is all used up, and then you know exactly what level to be looking for.

The change in pedal feel when you use up the last of the assist pressure is really completely unmissable. You get a rhythm going with your foot for those 30 or 40 pedal strokes, and the last ones are like gish, gish, gish, gish, gish, gish, gish, gish, BAM! and then you can hop to the front of the car on your good foot and check the level with complete confidence.

-Chap

 

The brakes worked fine and I drove for years with just the occasional 'brake' light flash in cold weather in a hard turn. At this point, the original symptoms are gone and I'm a happy camper. <GRINS>

Bob Wilson

 

It would be helpful if you could say something more descriptive about the vibrating. Is it something you feel chiefly in the steering wheel, and while making turns at especially low speeds, as when parking or unparking? If so, is it really a rapid twisting of the wheel back and forth (i.e., in the way a steering wheel usually turns, not just, say, the whole thing shivering up and down, or something)? Like the wheel quickly twisting itself back and forth in your hands at about the speed of a wet dog shaking? Does it tend to dampen out pretty quickly if you just improve your grip on the wheel, but if you completely let go when a good one gets going, it might just sit there and shake itself for a second or more (giving itself away as a powered phenomenon)?

IF it is like that, then you're seeing the well-known steering gear torque sensor failure. The steering gear is one of several bits of the car built with a certain kind of electrical sensor that can get noisy over time, causing weird things to happen, depending on which sensor is involved. When it's the steering sensor, this is the weird thing that happens.

With all of the other similar sensors in the car, people have been routinely just taking them apart and cleaning the surfaces that get noisy, putting them back together, and calling it good. That hasn't been happening as much with the steering gear, just because it's a lot harder job. First the steering gear itself has to be disconnected from the wheel knuckles and suspension and steering column, and lowered out of the car, and then even once you're looking at it on the bench, until recently there was little published information on how you could take it apart to get to the torque sensor, in a way that wouldn't destroy it so you could put it back together.

Therefore, solutions along two lines have mostly been explored:

1. Replace the whole steering rack with a good one. This is the GOOD and FAST solution. It's what Toyota will do. They were doing it for free up through 31 December 2013, but that ship has now sailed. Now it is not cheap, because the part itself is four figures and, as you could guess from my description above, the labor isn't minor. It is also possible to get a remanufactured unit; Cardone sells one. (Clearly, that means somebody at Cardone did figure out how to take the thing apart and get to the torque sensor, but they didn't share that information with PriusChat.) Simply putting in a used rack could be a cheaper option, but a risky one: with that much labor involved, it would be no fun to put in a used rack and find it has the same problem already, or develops it soon.
2. Bob Wilson has been the chief proponent of a repair technique that might work electrically without needing any labor besides access to the wires right behind the glove box. It hasn't been tried a lot and so far the results seem a bit equivocal.

We've been working on learning more about the electrical properties of the sensor, which could lead to a couple of benefits: it might help guide improvements to the easy repair procedure Bob is interested in; it might also provide rules of thumb for testing a salvage rack with a simple multimeter to decide whether it's worth buying.

In the process of trying to do that, I finally did break down and buy the cheapest used rack I could find, just to try whether I could figure out how it comes apart and get to the torque sensor. It turns out I could, and while it's a bit of a delicate, several-step process, it's not really too bad.

Ironically, since then, I haven't had any time to get back to making the more precise electrical measurements, which were really the purpose of taking it apart in the first place. I'll get back to it eventually. But at least we do now have published information on how it comes apart, so if anybody facing the problem just wanted to clean and reassemble the sensor, there is now the possibility of doing that ... it's just a much more labor intensive, longer and more mechanically involved, version of doing the same thing with the other similar sensors on the car.

-Chap