P2B87: Coolant Pump A Underspeed

The coolant pump A runs below the calibrated minimum speed for the commanded duty. Mechanical resistance high or supply voltage low.

Most likely causes

• Mechanical load increased (binding)
• Supply voltage low under load

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 can trigger limp mode.

What each character of P2B87 means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• B: Subsystem depends on the code range
• 87: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2B87?

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 P2B87?

The most common causes are: mechanical load increased (binding); supply voltage low under load.

Related codes

• P2B9FCoolant Pump B Underspeed
• P2BA0Coolant Pump C Underspeed
• P2BA1Coolant Pump D Underspeed
• P2DF8Coolant Pump E Underspeed

Sources

• github.com: dtc database
• en.wikipedia.org: Water pump

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.