ECU malfunction Codes at 159,000 miles / Service

My 2005 Prius with 159,000 miles is a daily driver on a 100 mile round trip commute. I was using it as a postal delivery vehicle for nearly 4 years on a part-time basis and one year daily on a 54 mile route in the Adirondacks. Since last year, the Prius only does the commute as I now have a delivery vehicle. The car has been mostly trouble free with the exception of hub/bearing replacements, the left drive axle, and routine maintenance. The combination meter fails intermittently in all temperature ranges and is not limited to only cold weather.

Last week the combination meter failed again as I was leaving to replace a HID headlight in a buddy's 05 Prius. The return trip home was the same. Powered the car off and on three times with no change. The next morning, all was back to normal but the engine warning light remained on. This had never happened in the past.
After a week, I brought it down to get the trouble codes read with the OBDII. Results?
C1300: Malfunction in engine control unit caliper front 1;
C1253: Hydrobooster pump motor relay malfunction caliper front 3;
P0456:Evaporative emission control system pressure leak detected - small leak.

I am replacing the coil springs and struts as the left rear coil has recently broken. My appointment is on the 20th of this month.

The plugs and PCV valve have never been changed. I worry that at this point, the threads may very rusted and difficult to remove. Should I attempt this myself or let the dealer take care of it. Would like to replace them with Denso iridium tip plugs. Any thoughts?

History:
Mobil 1 5W30 oil/filter change every 5000 miles since new.
Left drive axle replaced @ 87,000 mi
Transaxle fluid replaced at 100,000 mi
Coolant flush/replacement at 100,000 mi
All recall work performed except floor mats (no need)
All filters replaced regularly (cabin and engine)
12v battery changed summer 2011 as a precaution due to age (did not experience problems)
Front brake pads replaced @80,000 miles
Exhaust system replacement at 124,000 mi. (Failure - rust out of main unit prior at the connector that allows the tailpipe to bolt on. I still have the main unit from the catalytic converter to the pipe. Next time it needs replacing, I will have a new tailpipe welded to the main unit.)

This car is in MINT condition - Heated smooth leather seating, spotless interior, No flaws, dents, scratches, etc. Looks new. No leaks. Averages 53 - 55mpg in temps above 50.

Any thoughts / recommendations? Could the emissions code be the result of deteriorating plugs?

 

Thanks Patrick! Already intended on clearing the codes to find out exactly what is happening. My impression was that ECU failure was relatively rare. I have not had any issues with the braking system and wonder if the ECU codes are from an old issue that resolved itself after front caliper removal and re-alignment of new brake pads a few years ago. At that time, ALL of the warning lights illuminated but cleared on their own after adjustment.

The gas cap was the first item checked. All appears fine. I have filled up a few times since - no change.

The plugs and PCV will be tackled this weekend. I am curious as to what I will find.

The car had 87,000 miles on it as of Jan 2011. Only in the last 2 years did I nearly double the mileage. I can honestly say that the car far outweighed my expectations! Who would have ever believed that this car could be capable of delivery in sub-zero temperatures on a daily basis through record snowfall the winter of 2010 - 2011! As I remember, there were only 2 clear, sunny days without ANY precipitation that winter! I do know that Toyota sold quite a few Prii the next Spring after my customers saw for themselves just how reliable and snow worthy this car had been!

 

A strange outcome to engine light on symptom: A few weeks ago I brought the car in for an alignment and was told that there was a broken rear coil spring on the car. Had to buy parts online (coil springs and struts) for both sides before setting up an appt. with the dealer as the weather is now too cold to be messing around with the car. The engine light remained on for the past few weeks since my last post.

Today was the day that the car was scheduled to be repaired. Upon completion of the work, the dealer reminded us (on the statement) that the engine light was on. The good news is that upon starting the car to leave the dealership, the engine light was no longer on. It is VERY unsettling to know that random codes could occur in response to a broken spring. I am thankful that i had the foresight to actually type out EXACTLY what I wanted the dealership to do and specify that all parts were supplied by me, that I was aware of the engine light and that they were not to do anything about it.Otherwise who knows what the bill would have been and what would have been charged. Dealerships can't be trusted as we all know...

While I was there, I did mention the recent recalls involving the hybrid water pump and the steering mechanism. I also mentioned the extended warranty on the combination meter. I was told that the first two are forthcoming (something that I already knew). On the other hand, I did print out the information from Prius Chat regarding the enhanced warranty on the CM which is VIN specific and asked if my Prius was on the list. I was told bluntly that there is no warranty on the CM and that the information from "those websites" is a lot of BS. Is there an official letter or copy thereof that could be posted to verify this? Should I call TMS directly? What are your thoughts?

 

A young groundhog. There were several living in the woods on our property. The offspring, once out of the nest and on their own would saunter over and "visit" anyone who happened to be outside. They are notorious for giving nasty bites so I put on gloves before attempting to pick this guy up while my wife took the picture.​

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I e-mailed Toyota and hope that my vehicle is included in the enhanced warranty. Thanks again for the input to all who responded.​

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The folks at Toyota did not clear the codes as I told them specifically that I knew about the problem and did not want them doing anything diagnostically. According to the service dept, the engine light was on when the car left the service bay. This was documented on the repair receipt. When the car was restarted when picked up about an hour later, the engine light was off. I'll just wait and see how things go.​

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In the past, I have had the headlight leveling warning light and the airbag warning lights illuminate. I have been able to successfully clear them after reading about similar problems within the genII forum - saving a lot of time and money.​

 

OK. So far so good. I called the dealership and was told that the codes were not cleared during service. (That would have added another $100.00 to the bill for diagnostic service). The repair work done to the car did not require disconnecting the battery.

At this point the engine warning light has stayed off. I can't help wonder if most of the problems that I've had in the past were due to an offset hit to the left front fender, wheel and driver's door in 2008 (at 32,000 mi) while I was delivering mail and driving up a steep hill. In my opinion, I believe that the coil spring may have cracked back then and gradually worsened over time. Not to mention the fact that a year after the accident , I wound up replacing the left drive axle and hubs on both sides as replacing items like that in pairs is best.

I was able to veer away from a direct hit and the front bumper and engine compartment were spared. Thankfully, I was driving from the passenger side. The guy who hit my car took a wide turn down the road on which I was driving and continued down the steep incline on the opposite side of the road headed straight for me! Since my view was blind due to the steepness of the incline as I headed up the hill, I had little time to react when he came into view as he was driving fast. I veered off the shoulder of the road as soon as I saw him and wound up in a farm field. The driver of the other vehicle told the state trooper that he was "checking the address of his next appointment' (he was a water softener tech) and did not know what he hit until he reached the bottom of the hill, got out of his car, and looked back. He was also unhurt. His car, however, was totaled - airbag deployed, front wheel was mangled, the windshield smashed, hood crushed, etc. etc. - a Hyundai.

Anyhow, the car drives better than ever and the warning light is off. Now to get to the recall issues and combination meter issue settled...

 

Codes appearing again...5 months later! After the previous posts, I thought that I was in the clear when the CEL went off after the dealer replaced the rear springs/struts. Still can't figure that one out...

Today on my long commute home (sunny and dry temps in the low 50s) the CEL appeared again. The codes pulled are the same ones that appeared 5 months ago (DTC C1253, DTC C1300, and DTC P0456) and the car continues to run without a problem.

What could be triggering the CEL and what is obviously "old codes" to reappear? I had not cleared the codes last time since the CEL went out on its own...

 

Sigh! Here we go again... CEL is off with no intervention after nearly 6 weeks... Noticed it off again last Saturday (May 25). On again off again with no explanation - This is the reason for me not getting it checked by Toyota. I can't take this car seriously anymore when the CEL illuminates. The 12v battery is fine - 22 months old. I guess it's just a quirk with this car. The gas cap is not the problem, either.

 

Headlight leveling sensor was replaced (by me) for about 179.00: new part + my labor. A relatively easy fix but that would not trigger the CEL. When I had the problem with the headlight leveling sensor, the MFD reported a problem and displayed the image. After a few cleanings, the sensor's arm became rigid and rusted. At that point, I purchased a new unit.

 

Car has always ridden fine. No change whether the CEL is illuminated or not. I am keeping a log of the codes and the dates when the CEL decides to activate. So far, so good. As long as it is off for its annual inspection I can live with it.

 

So far so good... until yesterday. Driving daily with no issues until parked for about 30 minutes. Started the car and... THE DREADED RED TRIANGLE! MFD indicates "PS" and the car has lost ALL power steering assist. The CEL remains off.
Called my local Toyota service dept located about 3 miles from home and was advised that I "might need an oil change or service which could have triggered the warning light." The guy obviously did not know the difference between the "Maintenance light, the CEL and the warning light. He also indicated that they could not get the car in for a week or so. Definitely NOT bringing the car there.
Contacted another dealership in the next state about an hour's drive away. Needless to say, that's where the Prius was taken. The dealership is far superior at diagnosing and repairing. Just wish it was closer to home.
Gave them a copy of all service records and what was done recently. Just waiting to see what they come up with and curious is this new problem is related somehow to the ongoing issue with the CEL.

 

I read the posts yesterday about the PS ECU and thought about getting replacing the unit myself before calling the dealer. Unfortunately, I don't have the time and need the car right away. Dealer called today to confirm that was the problem and the car should be ready tomorrow

 

All was well since June 2013 when the CEL decided to come out of hibernation while driving to work at 5:00am this morning. Outside temperature roughly 8 F. About 8 miles from home, CEL illuminates. I pull over, check the oil, check engine coolant level in the radiator (not just overflow tank), check for turbulence in the hybrid system coolant reservoir, check that the gas cap is tightened, and do a quick overall inspection of the engine compartment. All is well. Drove car an additional 3 miles to work and then home again about 6 hours later. CEL remained illuminated. No other codes. Rechecked what I had checked in the morning as now there was daylight to confirm that the fluids were to level and that there were no leaks. Drove to Advance Auto to retrieve codes. As follows: C1311, Po137, P0456.

Vehicle now has 220,000 miles. Since 2013, the aftermarket exhaust system (Eastern) has been replaced due to rust out. The muffler has also been replaced twice. The original exhaust system with no signs of rust / deterioration (except for the lack of the connector due to a rusted out pipe behind the connector's weld) was put back on the car and a new muffler welded directly to the pipe due to the lack of a connector. This was done back in September.It was noted at that time that there were slight cracks in the manifold that were "not of concern" at that time...

The previous codes: C1253 and C1300 that persisted several years ago have not returned and whatever issue that caused them to log, has resolved on its own (odd, don't you think?)

My last plan of attack will be to disconnect the battery to see if the codes clear and/or reappear.

I was reviewing what Patrick had written earlier regarding the code P0456 which I will look into if the codes reappear.

I researched the new codes and came up with the following:

DTC P0137: Oxygen Sensor Circuit Low Voltage Bank 1 Sensor 2
[from: http://engine-codes.com/p0137_2005_toyota_prius.html]

DTC C1311/12 : Open or short circuit in brake inhibit relay circuit [from Toyota Service News, Fall 2007]

Is the car safe to drive? It drives normally - no noise - no exhaust smoke - no problem with acceleration...

Are multiple codes triggered by one event? I would take a guess that the P0456 is code of most concern? I am also wondering if the "slight cracks" in the manifold are the culprit. After all, we have had wildly fluctuating temperatures here in the past week. 50 F last Sunday and down to -21 F by Thursday. Anyone have an idea of how I should proceed if the codes return?