A P0562 indicates system voltage is lower than the computer expects, which on a diesel usually points to a charging or battery problem rather than the engine itself.
What P0562 means
System Voltage Low is a diagnostic trouble code set when the monitored value falls outside its expected range. On the , it narrows the problem to a specific system, and reading it correctly prevents replacing good parts.
Common causes
- Failing alternator or charging fault
- Weak or failing batteries
- Corroded or loose battery and ground connections
- Worn serpentine belt slipping the alternator
Symptoms you may notice
- Dim lights and low dash voltage
- Slow cranking
- Battery or charging warning
- Electrical accessories behaving oddly
How to diagnose it
Measure charging-system voltage at idle and under load, and load-test the batteries. Low charging output points at the alternator or belt, while good charging with low resting voltage points at the batteries or connections.
How to fix it
Repair the charging fault, replace failing batteries as a matched pair, and clean the connections. On diesels with two batteries, replace them together. Verify healthy charging voltage after the repair.
Frequently asked questions
What causes P0562?
Low system voltage from a charging fault, weak batteries, a slipping belt, or corroded connections.
Is it the alternator?
Often. Low charging output at idle and under load points to the alternator or belt; verify with a voltage check.
Should I replace both batteries?
On a diesel with two batteries, replace them as a matched pair so one weak battery does not drag down the other.
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