Common 2G Problems, and What to Do About Them...

Evan Fusco had requested a compilation of 2G known problems, so I'm starting this thread to capture commonly-seen issues.

Problem: Car won't start
Symptoms: There are several possible reasons for a no-start situation. The most likely would be lack of fuel or a dead 12V auxiliary battery. If your fuel gauge shows two bars or less, then suspect insufficient fuel. If you note that cabin lighting is dimmer than normal or if the headlights are dim, then suspect a marginal 12V battery.
Frequency: N/A
Diagnostic: Variable, depending upon the root cause
Cure: Add fuel or replace the battery as appropriate. Note that if you add less than 3 gallons of fuel, the system may not recognize this addition. Then you'll have to disconnect the 12V auxiliary battery negative terminal for a few minutes, then reconnect. This will force the gas gauge to register correctly.
Other information/Alternate diagnosis possible: If the fuel level is sufficient and the 12V battery is OK, then more digging will be required. Open the hood and look for loose wiring harness connectors especially at the fuel injectors and the spark igniters.

If it has been raining recently, then it is possible that water may have dripped from the cowl onto the engine valve cover, and then into the spark plug wells causing engine misfire or no-start.

It is also possible that the throttle body interior and throttle plate require cleaning, if sufficient black gunk has accumulated. To inspect this, remove the air cleaner housing and rotate the spring-loaded throttle shaft while the car is IG-OFF. Use a flashlight to illuminate the interior of the throttle body, looking for this gunk on the throttle plate edges and the throttle body interior. If present, you can clean it off using throttle body cleaner (use the minimum necessary cleaner fluid, and don't get the mass air flow sensor wet. This is attached to the air cleaner housing and protrudes into the airflow leading down into the throttle body.)

The mass air flow sensor may require cleaning. A couple of screws secure this part to the air cleaner housing. Carefully remove the sensor and use MAF cleaner to clean off the wires and the bulb that senses ambient air temp. Make sure the O-ring is in good condition before reinstalling the MAF sensor.

Other reasons for no-start include oil viscosity which is greater than 5W-30 or excessive oil level. If the iridium spark plugs have not been replaced on schedule (every 120K miles) then this needs to be done. The engine air filter should not be excessively dirty.

If you see no obvious problem, then it is time to have the car towed to your local Toyota dealer.

Problem: Car won't shut off
Symptoms: When the car is READY and the POWER button is depressed, the car will not shift into P and move from READY to IG-OFF.
Frequency: Intermittent
Diagnostic: No DTC will be posted
Cure: For temporary relief, hold the POWER button down for several seconds until the car becomes IG-OFF. The permanent cure is to have the combination meter assembly replaced (this displays the speedometer, odometer, fuel gauge, warning lights, etc.)
Other information/Alternate diagnosis possible: This issue has been appearing on newer model years, particularly 2007-2009. Usually this problem will be accompanied by the combination meter going blank on an intermittent basis. The reason for the problem appears to be that the combination meter has an intermittent connection within and loses vehicle speed information. The POWER control circuitry will not move from READY to IG-OFF if the car's speed is indeterminate.

Problem: Car loses power. Master warning light (red triangle) appears. Brake and VSC lights may appear.
Symptoms: See above
Frequency: After car has been driven for a while, especially in hot weather
Diagnostic: DTC P0A93, Inverter Cooling Performance
Cure: Replace inverter coolant pump
Other information/Alternate diagnosis possible: This is a popular reason for Prius to stop dead, usually in hot summer weather. We've seen a sufficient number of inverter coolant pump failures so I would say that if you have more than 100K miles logged and you wish to keep your car in top condition, consider replacing this pump now as a preventive maintenance move.

Problem: 12V auxiliary battery failure
Symptoms: Unusual MFD warning messages. Weak cabin lights and headlights.
Frequency: May be intermittent initially
Diagnostic: Measure battery open-circuit voltage. 12.6VDC or greater indicates the battery is fully charged. 12.2VDC indicates 50% charge. However, note that battery voltage is not a perfect indicator of battery health as excessive internal resistance will result in the battery not being able to deliver sufficient current under load.
Cure: Replace the battery. The correct Toyota battery can be purchased at your Toyota dealer's parts counter. Note that two sizes are available; the smaller size is for base models while the larger size is for models with the Smart Entry / Smart Start system.

Some posters have been very happy with the Optima battery, but this requires installation of a new positive battery terminal connector and replacement of the negative battery cable.
Other information/Alternate diagnosis possible: If you have weird electrical problems and the battery is more than 3 years old, I suggest replacing it as a preventive measure and to rule that out as a cause of the problems.

Even if your car currently doesn't demonstrate weird problems; if you would be unduly inconvenienced by a dead 12V auxiliary battery, then I suggest you replace the battery every three to four years if you live in very hot or very cold climates; and every four to five years if you live in an area with moderate climate.

Problem: SmartKey-equipped Prius makes unusual beep sound upon shut down.
Symptoms: Beep sound is new, not previously heard
Frequency: N/A
Diagnostic: N/A
Cure: Replace fob battery
Other information/Alternate diagnosis possible: The battery costs around $5 or less at your friendly drugstore. If you like to do preventive maintenance, I suggest that you replace the fob battery every three years instead of waiting for the fob to stop working.

Problem: Traction battery failure
Symptoms: MFD traction battery or hybrid vehicle warning icon will appear. Engine will run more than normal.
Frequency: Will be a solid failure, not likely to be intermittent
Diagnostic: DTC P0A7F (which shows excessive internal battery resistance) and P0A80 (uneven battery module voltages) are likely DTC codes. P3011 through P3024 may also appear to show which battery block has failed.
Cure: Replace traction battery; consider purchase and installation of a salvage battery if cost of new battery is prohibitive
Other information/Alternate diagnosis possible: Need to ensure that the battery ECU or the inverter are not causing the problem.

Problem: MFD unresponsive
Symptoms: Unusual warning messages appear, having to do with the air conditioning system for example. The screen does not update as quickly as it should. The touchscreen controls do not respond to your touch.
Frequency: Initially intermittent, will eventually become a solid failure. Symptoms are usually worse in cold weather.
Diagnostic: N/A
Cure: Replace the MFD, ask the dealer to install a remanufactured unit to save considerable $$$.
Other information/Alternate diagnosis possible: This issue primarily affects 2004-2005 model year vehicles. If you wish to effect a DIY repair, look up Hobbit's website on this subject: http://www.techno-fandom.org/~hobbit/cars/mfd/

 

Hi Gene,

If you don't see any warning lights or warning messages on the MFD display, then no worries. Depending upon ambient temps, battery SOC, etc., the engine may run more or less than "normal".

To Bob64, dogfriend, and qbee42: Great additions to the list, keep them coming!

 

Find the dashboard lighting dimmer control to the left of the steering column, and adjust it so that the dashboard lighting meets your needs. If that control doesn't work, then a visit to your dealer is in order.