P26CF: Engine Coolant Pump Control Module System Voltage

Smart coolant pumps carry their own electronics, which measure the supply voltage they receive. P26CF is the general code for that voltage when it is implausible but cannot be assigned to too low or too high. No manufacturer documents P26CF itself in public. Ford's hybrid OBD summaries show the principle with the sister codes P26D0 and P26D1: the pump module sends its electronics voltage over LIN, and the PCM compares it with its own battery reading. CARB requires electronic components that affect emissions to be checked for plausibility. A general system voltage fault usually points to a shared cause – loose grounds, a weak battery, charging problems or intermittent contact – rather than to the pump. The pump may reduce its output or stop.

Symptoms

• Check engine lamp on
• Other voltage-related codes stored at the same time

Most likely causes

• Loose, corroded or intermittent pump supply or ground connection
• Weak battery or charging system fault
• Faulty voltage measurement in the pump electronics

What to check, in order

Start with the simplest. You can tick off each step.

1. With the engine cold, check the coolant level; never do this when the system is hot
2. Check the actual temperature in live data
3. Make sure the fan comes on when it should
4. Check the thermostat and connector
5. Measure the sensor and replace it if its readings do not make sense

Good to know

• Repair difficulty: medium
• It affects emissions.

What each character of P26CF means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 6: Control modules and outputs
• CF: Specific fault in that system

Frequently asked questions

Can I keep driving with code P26CF?

Watch the temperature gauge. If it climbs or a warning appears, stop the car in a safe place and turn off the engine: overheating can cause serious damage.

What causes code P26CF?

The most common causes are: loose, corroded or intermittent pump supply or ground connection; weak battery or charging system fault; faulty voltage measurement in the pump electronics.

Related codes

• P26D0Engine Coolant Pump Control Module System Voltage Low
• P26D1Engine Coolant Pump Control Module System Voltage High
• P26D3Engine Coolant Pump Supply Voltage Circuit
• P0562System Voltage Low
• P0563System Voltage High

Sources

• law.cornell.edu: 13 CCR 1968.2
• fordservicecontent.com: OBDSM1901 HEV

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.