Hybrid Vehicle Diagnostic Trouble Codes

When a “check engine” light appears on your hybrid vehicle’s dashboard, it could indicate one of many different problems. Don’t delay, ignore it, or go to a shop that does not specialize in HEVs. Our team of hybrid experts can resolve your problem and get you back on the road with confidence.  

By using a scanner (can be found at most auto parts stores), vehicle owners and shops can pinpoint what issue the car is detecting. Here we list some of the most common codes from Toyota, Lexus, and Prius vehicles. This post is intended as an educational resource. Do not service hybrid batteries without adequate training and always use proper safety equipment.

P0A80 CODE (Replace Hybrid Battery Pack)

This common code indicates an issue with your hybrid battery pack and is often accompanied by other diagnostic codes. Many times, the accompanying code will be a P3XXX code meaning that the voltage of a battery block is out-of-balance with other blocks. Occasionally, the P0A80 code can indicate a problem with the 12V battery or regenerative braking issue.

P3011-P3024 (Battery Block Becomes Weak)

These common codes occur when the voltages of the battery blocks become unbalanced. When the difference in voltage between the highest and lowest voltage blocks (pair of two modules in series) becomes high enough, this code is triggered. The final two digits of the code corresponding to the number of the block, which is at a low voltage. For example, P3011 indicates battery block 1 becomes weak, P3012 indicates battery block 2 becomes weak, etc.

P0AA6 (Hybrid Battery Voltage System Isolation Fault)

This dangerous fault code appears when the high voltage system is no longer isolated from the rest of the car as it should be. High voltage could be leaking to the chassis or any other part of the vehicle. This could result from bad wiring or an electrolyte leak from one of the battery modules. Electrolyte which leaks from the battery can create a direct connection between the high voltage system and the undercarriage of the car, which makes working on it very dangerous. Make sure to check the bottom of modules for leaks and always use proper safety equipment.

P0A7F (Hybrid Battery Pack Deterioration)

The resistance of one of the modules in the battery pack is too high, as calculated by the ECU (Electronic Control Unit). The only way to determine which module is the offender is to use a voltmeter to test.

P0A81 - P0A85 (Battery Cooling Fan)

Any of these four codes point toward the cooling fan. They indicate that the motor voltage is too low, or that the expected temperature of the batteries is beginning to rise.

P0A93 (Inverter Cooling System)

For this code, check 1) HV coolant level & hose, 2) water pump connector & assembly, 3) cooling fan motor.

P3030 (High Voltage Line Snapped)

The battery ECU is disconnected from one or more of the battery blocks (diagnostically). Within the vehicle, there is a wire which connects each battery block to the ECU. This wire is for diagnostics and is how voltages are measured. When this code appears, using a scan tool to monitor individual battery block voltages will point out which connection(s) have become broken.

C1241 (Low Battery Positive Voltage)

This indicates an issue with the 12V battery. Often misinterpreted as a hybrid battery code due to its “low voltage” description.

What to do now?

If you are experiencing an issue with your hybrid vehicle or have determined one of these codes, we can help you fix the problem. Our team of hybrid battery mechanics can come right to you with our onsite, mobile service. Stay in the comfort of your home, office, or school, and we’ll come to you. We can perform onsite diagnosis, repair, and even do a complete hybrid battery exchange. We offer new and high-quality reconditioned hybrid batteries at a fraction of the cost of a new OEM battery.

To learn more or speak with a specialist, visit www.hybridbattery911.com

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