P0C0B – Drive Motor “A” Inverter Temperature Sensor Circuit

P0C0B is a hybrid/EV trouble code that points to a problem inside the high-voltage battery pack, specifically with one of the internal temperature sensors. When this code sets, your car’s control modules are telling you they don’t trust the temperature reading of a particular battery section, which can affect charging, power delivery, and battery life. You might notice warning lights, reduced performance, or the car refusing to go “Ready.” This isn’t a code to ignore, because high-voltage battery protection is a top priority for your vehicle.

What Does P0C0B Mean?

P0C0B is a generic OBD-II hybrid/EV diagnostic trouble code that typically translates to something like “Hybrid/EV Battery Temperature Sensor ‘B’ Circuit Range/Performance.” The exact wording varies by manufacturer, but the idea is the same: the ECU (often the hybrid control module or battery ECU) is seeing a temperature signal that’s out of the expected range or behaving abnormally for one of the battery sensors.

The high-voltage battery pack uses multiple temperature sensors to manage cooling, charging, and power output. If one sensor (often labeled “B”) reports unrealistic values, the system goes into protection mode, stores P0C0B, and may limit performance or disable the hybrid/EV system to prevent battery damage or a thermal event.

Quick Reference

• Code: P0C0B
• Definition: Hybrid/EV battery temperature sensor “B” circuit range/performance (or similar wording)
• System: High-voltage battery / hybrid or EV control
• Severity: Moderate to high – can lead to reduced power or no-start
• Common Fixes: Repair wiring, replace battery temperature sensor, repair or replace battery pack or battery ECU

Real-World Example / Field Notes

In the shop, I usually see P0C0B on higher-mileage hybrids or early EVs that have lived in hot climates. A typical case: the customer complains the car sometimes won’t go into “Ready,” or the engine runs more than usual and the EV mode is limited. The dash may show a hybrid system warning. Scanning the ECU shows P0C0B with a freeze frame indicating a battery temperature reading that doesn’t match the others. After checking live data, one sensor reads -40°F or 300°F while the rest look normal, pointing to either a failed sensor or a wiring issue inside the battery case. Once the sensor or harness is repaired, the car returns to normal behavior and the warning disappears.

Symptoms of P0C0B

• Warning lights: Hybrid system warning, check engine light, or EV system malfunction indicator illuminated.
• Reduced power: The car may enter a limp mode with limited acceleration to protect the battery.
• No “Ready” condition: The vehicle may refuse to go into Ready or EV mode, acting like it won’t start.
• High engine use: On hybrids, the gasoline engine may run more often and EV-only operation is restricted.
• Charging issues: Plug-in hybrids or EVs may have charging faults or reduced charging rates.
• Cooling fan behavior: Battery or cooling system fans running more often or at high speed.
• Other battery codes: Additional hybrid/EV battery DTCs may be stored along with P0C0B.

Common Causes of P0C0B

Most Common Causes

• Failed high-voltage battery temperature sensor “B” inside the battery pack.
• Open, shorted, or high-resistance wiring between the temperature sensor and the battery ECU.
• Corroded or loose connectors at the battery pack or battery ECU.
• Internal damage to the battery pack harness from heat, vibration, or moisture intrusion.
• Battery ECU (battery management module) software seeing out-of-range data due to sensor drift or failure.

Less Common Causes

• Internal fault in the battery ECU or hybrid control module.
• Previous battery repairs or rebuilds where the harness or sensor wasn’t correctly routed or secured.
• Water damage in the rear of the vehicle (leaky tail lights, hatch seals) affecting the battery pack area.
• Severe battery overheating event causing both cell and sensor damage.
• Incorrect or incompatible replacement battery pack or module assembly.

Diagnosis: Step-by-Step Guide

To diagnose P0C0B properly, you’ll want a good scan tool that can read hybrid/EV data, a digital multimeter, and ideally access to factory service information. High-voltage work is dangerous, so if you’re not trained and equipped, let a qualified hybrid/EV technician handle anything inside the battery pack.

1. Verify the code and record data. Connect a scan tool, confirm P0C0B, and note freeze frame data (battery temperature readings, state of charge, ambient temp). Check for related battery or hybrid system codes.
2. Check live data for battery temperatures. Look at all battery temperature sensors in live data. A sensor reading -40°F, 300°F, or a value that doesn’t move while others change is a strong clue.
3. Compare to ambient temperature. With the car cold, most battery temps should be close to outside temperature. One sensor that’s way off suggests a circuit or sensor fault.
4. Inspect connectors (low-voltage side). With the vehicle powered down and safe, inspect the accessible connectors at the battery ECU and any external harness plugs for corrosion, bent pins, or moisture.
5. Check service information. Use wiring diagrams to identify which pins are for temperature sensor “B.” Many systems use a thermistor with a 5V reference and ground or a resistance-only circuit.
6. Test resistance or voltage. Following factory procedures and safety steps, measure resistance of the suspect sensor circuit or voltage at the ECU connector. Compare to spec at known temperatures (often given in a temperature/resistance chart).
7. Wiggle test the harness. While watching live data or meter readings, gently move the harness and connectors. If the reading jumps, you may have an intermittent open or short.
8. Inspect inside the battery pack (if qualified). If all external checks pass, the fault may be inside the battery case. This requires high-voltage shut-down procedures, insulated tools, and PPE. A hybrid/EV specialist should inspect the internal harness and sensor.
9. Check for TSBs and software updates. Some manufacturers release technical service bulletins or ECU reflash updates to address false P0C0B triggers or sensor calibration issues.
10. Confirm the repair. After any repair, clear codes, perform a road test or drive cycle, and recheck for pending codes and battery temperature data stability.

Pro tip: Before condemning the battery pack itself, always compare all temperature sensors side-by-side in live data. One outlier is usually a sensor or wiring issue, not an entire pack failure.

Possible Fixes & Repair Costs

Fixing P0C0B usually involves restoring accurate temperature information to the battery ECU. That can be as simple as repairing a connector or as involved as replacing the battery pack. Typical repairs include:

• Cleaning or repairing corroded connectors and terminals.
• Repairing or replacing the internal or external battery temperature sensor harness.
• Replacing the faulty battery temperature sensor “B” (when serviceable separately).
• Replacing or rebuilding the high-voltage battery pack if damage is extensive.
• Updating or replacing the battery ECU or hybrid control module if confirmed faulty.

Costs vary widely. A simple wiring or connector repair may run $150–$400. Replacing a serviceable temperature sensor or internal harness can range from $300–$900 depending on labor time and access. If the high-voltage battery pack needs replacement, you could be looking at $2,000–$5,000+ for a new OEM pack, or $1,200–$3,000 for a remanufactured unit. Labor rates, parts availability, and whether you use OEM or aftermarket components all affect the final bill.

Can I Still Drive With P0C0B?

In many cases, you can still drive with P0C0B, but the car may limit power or disable EV mode to protect the battery. Some vehicles will continue to operate with reduced performance, while others may refuse to go into “Ready” once the fault becomes severe or intermittent. Short-term driving to get to a repair shop is usually possible, but you shouldn’t ignore the code for long. A faulty temperature reading can prevent the system from cooling or managing the battery correctly, increasing the risk of further damage.

What Happens If You Ignore P0C0B?

If you ignore P0C0B, the hybrid/EV system may progressively restrict power, disable charging or EV mode, and eventually prevent the car from starting. More importantly, inaccurate battery temperature data can allow the pack to overheat or charge incorrectly, shortening battery life and potentially leading to costly pack replacement. Addressing the issue early is almost always cheaper than waiting for a major failure.

Last updated: January 22, 2026

Vehicles Commonly Affected by P0C0B

P0C0B shows up most often on hybrids and EVs from manufacturers like Toyota and Lexus (Prius, Camry Hybrid, Highlander Hybrid, RX and ES hybrids), Honda (Insight, Accord Hybrid), Ford (Fusion Hybrid, C-Max, Escape Hybrid), and GM (Chevrolet Volt, Malibu Hybrid). It can also appear on some Nissan, Hyundai, Kia, and other EV models. Any vehicle with a high-voltage battery pack and multiple temperature sensors can store this code when the battery management system detects a bad reading from one sensor circuit.