P0562 – System Voltage Low

P0562 is a very common OBD-II trouble code that points to a low system voltage problem. In plain terms, your car’s electrical system isn’t getting the power it should, and your ECU is not happy about it. This can be as simple as a weak battery or as serious as a failing alternator or wiring issue. If you’re seeing P0562, you might also notice dim lights, hard starting, or random warning lights. In this guide, you’ll learn what P0562 means, how to diagnose it, and the most effective ways to fix it.

What Does P0562 Mean?

P0562 is defined as “System Voltage Low.” Your vehicle’s powertrain control module (PCM) or engine control unit (ECU) constantly monitors battery and charging system voltage. When it sees voltage drop below a calibrated threshold for a set amount of time, it stores P0562 and usually turns on the check engine light.

Most vehicles expect system voltage to stay around 13.5–14.7 volts with the engine running. If the ECU sees voltage significantly below that range, it assumes there’s a charging or power supply problem and sets this code.

Quick Reference

  • Code: P0562 – System Voltage Low
  • Typical causes: Weak battery, bad alternator, loose/corroded connections, wiring faults
  • Common symptoms: Dim lights, hard starting, stalling, warning lights
  • Risk level: Moderate to high – can leave you stranded if ignored
  • Usual fixes: Charge/replace battery, repair/replace alternator, clean/repair wiring and grounds

Real-World Example / Field Notes

In the shop, I see P0562 most often when an alternator is slowly dying or after someone installs a new battery without cleaning the terminals. A typical case: customer complains of dim headlights at idle and a battery light that flickers on and off. Scan tool shows P0562 stored and charging voltage around 11.8–12.2 volts with the engine running. A quick test confirms the alternator isn’t producing enough output. Replacing the alternator and cleaning all main connections clears the code and restores normal voltage.

Symptoms of P0562

  • Check engine light illuminated, sometimes along with battery or charging system warning lights.
  • Dim headlights or interior lights, especially at idle or with multiple accessories on.
  • Hard starting or no-start condition after the vehicle sits, due to a discharged battery.
  • Engine stalling at idle or while driving, particularly when electrical load is high.
  • Erratic gauges or warning lights, such as flickering cluster, ABS, or traction lights.
  • Weak electrical accessories, like slow power windows, weak blower motor, or sluggish wipers.
  • Poor transmission behavior, including harsh shifts or stuck in limp mode on some vehicles.
  • Reduced fuel economy or performance as the ECU cuts back functions to protect the system.

Common Causes of P0562

Most Common Causes

  • Failing alternator – The alternator is not producing enough voltage or current to keep the battery and system charged, especially under load.
  • Weak or dead battery – A battery with low capacity or internal damage can drag system voltage down and trigger P0562.
  • Loose or corroded battery terminals – Poor contact at the battery posts increases resistance and causes voltage drop.
  • Bad main ground connections – Corroded or loose engine and chassis grounds can cause low voltage readings at the ECU.
  • High electrical load with marginal charging system – Running lights, HVAC, heated seats, and audio at once can expose a weak alternator or battery.

Less Common Causes

  • Damaged wiring harness – Broken, chafed, or corroded power or ground wires between the battery, alternator, and ECU.
  • Faulty voltage regulator – On many modern cars, the regulator is built into the alternator or controlled by the ECU; if it fails, voltage may stay low.
  • ECU power supply issues – Blown fuses, poor relay contacts, or internal ECU faults affecting its voltage sense circuit.
  • Aftermarket accessories – Poorly installed stereos, amplifiers, lighting kits, or remote starts drawing excessive current or spliced into critical circuits.
  • Internal short or parasitic drain – A component that is partially shorted can pull system voltage down while running.

Diagnosis: Step-by-Step Guide

To diagnose P0562 properly, you’ll want a quality digital multimeter, a basic OBD-II scan tool (preferably with live data and Mode $06), and access to wiring diagrams or service info for your vehicle. Safety first: wear eye protection and be careful around moving engine parts and the battery.

  1. Confirm the code and check for companions. Scan the vehicle for codes. Note any related charging or communication codes (like P0560, P0563, U-codes). This helps narrow down whether it’s a simple voltage issue or part of a larger electrical problem.
  2. Check battery state of charge. With the engine off, measure battery voltage at the terminals. Around 12.6 V indicates a healthy, fully charged battery. Anything under about 12.2 V suggests a low or weak battery that needs charging or testing.
  3. Inspect battery terminals and cables. Look for corrosion, loose clamps, frayed cables, and green/white buildup. Clean the terminals, tighten connections, and make sure the cables are not cracked or swollen.
  4. Test charging voltage at idle. Start the engine and measure voltage at the battery. You should see roughly 13.5–14.7 V. If it stays near 12 V or drops below, the alternator or its wiring is suspect.
  5. Load test the charging system. Turn on headlights, rear defogger, blower on high, and measure again. Voltage should stay above about 13.0 V. If it drops significantly, the alternator may not handle load or the belt may be slipping.
  6. Inspect drive belt and connections. Check the serpentine belt for cracks, glazing, or looseness. A slipping belt can cause low alternator output. Also inspect the alternator plug and main output cable for looseness or corrosion.
  7. Check grounds and power feeds. Using the wiring diagram, locate main engine and chassis grounds. Make sure they’re tight, clean, and free of rust. Perform a voltage drop test (measure voltage between battery negative and engine block with engine running) – it should be very low (ideally under 0.2 V).
  8. Use scan tool live data. Compare the ECU’s reported system voltage to your multimeter reading at the battery. If the ECU sees much lower voltage than reality, there may be wiring, fuse, or internal ECU issues in the sense circuit.
  9. Check for parasitic draw (if needed). If the battery repeatedly dies, perform a key-off current draw test. Excessive draw can keep the system in a low-voltage state and repeatedly trigger P0562.
  10. Clear codes and retest. After repairs or adjustments, clear the code, drive the vehicle, and monitor voltage and readiness monitors. If P0562 does not return and voltage stays stable, the issue is resolved.

Pro tip: Don’t just throw an alternator at the problem. A weak or internally shorted battery can overload and kill a new alternator. Always test and verify both the battery and alternator before replacing parts.

Possible Fixes & Repair Costs

Most P0562 repairs involve restoring proper charging system operation and clean power delivery to the ECU. Costs vary widely depending on what you find during diagnosis, parts quality, and labor rates in your area.

  • Battery charge or replacement – Charging is often free or low-cost; a new battery typically runs $120–$300 installed, depending on size and brand.
  • Alternator replacement – On most cars, expect $350–$900 parts and labor. Luxury or difficult-access vehicles can exceed $1,000.
  • Cleaning/repairing battery terminals and grounds – Often $50–$150 at a shop; sometimes done as part of another repair.
  • Repairing wiring or connectors – Simple repairs can be $100–$250; complex harness issues may run higher if extensive tracing is needed.
  • ECU or voltage regulator issues – If integrated into the alternator, it’s included in alternator cost. If ECU-related, reprogramming or replacement can range from $300–$1,200+.

In general, you’re looking at typical repair ranges from about $150 on the low end (cleaning and minor wiring) up to $900 or more for alternator and battery replacement. Final cost depends on parts quality (OEM vs aftermarket), labor time, and how much corrosion or wiring damage is present.

Can I Still Drive With P0562?

You can sometimes drive for a short period with P0562, but it’s risky. Low system voltage can cause the engine to stall without warning, power steering to get heavy, and safety systems like ABS or airbags to behave unpredictably. If the alternator has failed, you’re running purely on battery power, and once that’s drained, the car will shut off. If you must drive, keep trips short, turn off non-essential electrical loads, and head directly to a shop or home to diagnose the issue as soon as possible.

What Happens If You Ignore P0562?

Ignoring P0562 can lead to a completely dead battery, repeated no-start situations, and being stranded. Prolonged low voltage can also damage the alternator, ECU, and other sensitive electronics. Over time, you may see more warning lights, poor drivability, and higher repair bills than if you had addressed the problem early.

Related Codes

  • P0574 – Cruise Control System Vehicle Speed Too High
  • P0573 – Brake Switch “A” Circuit High
  • P0572 – Brake Switch “A” Circuit Low
  • P0571 – Brake Switch “A” Circuit
  • P0570 – Cruise Control Accelerate Signal
  • P0569 – Cruise Control Coast Signal
  • P0568 – Cruise Control Set Signal
  • P0567 – Cruise Control Resume Signal
  • P0566 – Cruise Control Off Signal
  • P0565 – Cruise Control On Signal

Key Takeaways

  • P0562 means your vehicle’s ECU has detected system voltage that’s too low for safe, reliable operation.
  • The most common culprits are a failing alternator, weak battery, or poor connections at the battery and grounds.
  • Symptoms can range from dim lights and hard starting to stalling and multiple warning lights.
  • Proper diagnosis with a multimeter and scan tool is critical before replacing expensive parts.
  • Typical repair costs range from around $150 to $900+, depending on whether you need wiring clean-up, a battery, an alternator, or all of the above.
  • Don’t ignore P0562; fixing it early helps prevent breakdowns and protects sensitive electronics.

Vehicles Commonly Affected by P0562

P0562 shows up across a wide range of makes because every modern vehicle relies heavily on stable system voltage. In practice, it’s especially common on:

  • Domestic brands: Ford, Chevrolet, GMC, Dodge, Chrysler, and Jeep trucks and SUVs, particularly with higher electrical loads.
  • Asian brands: Honda, Acura, Toyota, Lexus, Nissan, Hyundai, and Kia sedans and crossovers.
  • European brands: Volkswagen, Audi, BMW, and Mercedes-Benz, where alternator and battery management systems are more complex.
  • Work vehicles: Pickup trucks, vans, and fleet vehicles that run lots of accessories (plows, inverters, lighting, power tools).
  • Older high-mileage cars: Any vehicle over 8–10 years old with original charging components is more likely to show P0562 as parts wear out.

FAQ

Can P0562 be caused by a bad battery?

Yes. A weak or internally damaged battery can drag system voltage down enough for the ECU to set P0562, especially during starting or with high electrical loads. Always test the battery’s state of charge and load capacity before replacing other components.

Is P0562 always an alternator problem?

No. While a failing alternator is one of the most common causes, P0562 can also be triggered by loose or corroded connections, bad grounds, wiring issues, or even an ECU power supply problem. That’s why voltage testing and visual inspection are so important.

How do I clear P0562 after fixing the problem?

After you repair the underlying issue, use an OBD-II scan tool to clear the code. Then drive the vehicle through a normal drive cycle while monitoring system voltage. If voltage stays within spec and the code does not return, the fix was successful.

Can low system voltage damage my ECU?

It can, especially if the voltage fluctuates wildly or drops very low repeatedly. Modern ECUs are somewhat protected, but running a vehicle for long periods with poor charging can stress the ECU and other modules. Addressing P0562 promptly helps avoid expensive electronic failures.

How long can I drive with P0562 before the car dies?

There’s no exact time because it depends on battery capacity, alternator output, and electrical load. With a failed alternator and a fully charged battery, you might get anywhere from a few minutes to an hour or two. Once the battery voltage falls below a critical level, the engine will stall and you won’t be able to restart.