P2B31: Fan 2 Performance/Stuck Off

P2B31 is the functional code for a second radiator fan: its circuits test fine (otherwise P0481, P0693 or P0694 would be set), yet the fan turns too slowly or not at all when commanded. Twin-fan cooling packs usually run fan 2 for high load or A/C demand, so a failure tends to show up only in heat or traffic. No manufacturer documents P2B31 publicly. FCA's 2.0 L Alfa Romeo models use the fan 1 sibling P2B2F with the MIL, and Audi's e-tron GT bulletins show how debris from the wheel housing can jam either of its two fans. CARB requires output components to be monitored for functional response where feasible. A worn motor, blocked blades or a fan module that stays off are the likely causes. Expect rising temperatures under load. Its stuck-on twin is P2B32.

Medium severity. Can I keep driving?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.

Symptoms

MIL or cooling warning
Temperature climbing at high load or with A/C on

Most likely causes

Fan 2 motor worn, seized or jammed by debris
Fan module or relay for fan 2 not switching on
Weak supply or ground to fan 2

What to check, in order

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

With the engine cold, check the coolant level; never do this when the system is hot
Compare the reading with other engine data while varying the engine speed.
Check the actual temperature in live data
Make sure the fan comes on when it should
Check the thermostat and connector
Measure the sensor and replace it if its readings do not make sense

Good to know

Repair difficulty: medium
It can trigger limp mode.
It affects emissions.

What each character of P2B31 means

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

Frequently asked questions

Can I keep driving with code P2B31?

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 P2B31?

The most common causes are: fan 2 motor worn, seized or jammed by debris; fan module or relay for fan 2 not switching on; weak supply or ground to fan 2.

Related codes

Sources

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.