P26AD code meaning
Engine Coolant Bypass Valve B Control Circuit Low
Powertrain system Generic code P26xx codes Check engine light
What P26AD means
P26AD indicates a drive line of valve B pulled to ground. GM uses the code differently from the title: on the second-generation Volt (2016 table, VICM) the single coolant bypass valve has an H-bridge motor with two drive lines, and P26AD stands for driver 2 reporting a short to low while the valve is commanded toward the high position. Four failures in five samples at 100 ms set it as Type B; it is one of the codes that blocks P26A5, P26A9 and P15C5. Ford's 2014 gasoline list and its 2020–2025 summaries do not use P26AD. CARB requires output circuit faults to be detected but does not demand separate codes for each fault type. Expect a chafed wire to ground or a shorted motor winding.
P26AD at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P26AD
- Check engine light after two drives (GM)
- Valve no longer moves, heating or warm-up affected
Common causes of P26AD
- Most likelyDrive wire chafed and shorted to ground
- PossibleShorted valve motor winding
- Less likelyCoolant or water in the connector creating a leak path
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Coolant bypass valve bSolenoidWiring harness
What each part of P26AD means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 6 | Area: computer (engine control module) and output circuits. |
| AD | The exact fault in that area. |
What to do next
- Note P26AD and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P26AD
What does P26AD mean?
P26AD means "Engine Coolant Bypass Valve B Control Circuit Low". P26AD indicates a drive line of valve B pulled to ground. It is a generic code, so it means the same on every make.
Is it safe to drive with P26AD?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P26AD fail an emissions test?
Yes, it can. P26AD is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P26AD to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. This is a job for a workshop.
Will P26AD clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.