P2C28: Fuel Injector Group B Supply Sense Circuit High

Voltage on the supply sense circuit of fuel injector group B is above the expected window. Indicates overvoltage or wire shorted to B+.

Medium severity. Can I keep driving?Drive as little as possible and go to a repair shop. If you smell fuel or the engine is shaking badly, do not keep driving.

Symptoms

Check engine light on
Misfire or rough idle on the affected cylinder
Increased fuel consumption
Possible fuel smell or smoke from exhaust

Most likely causes

Alternator regulator drift - overvoltage
Sense wire shorted to B+
Connector pins corroded - high contact resistance

What to check, in order

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

Check the connector and wiring of the injector indicated
Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
Measure the resistance and compare it with the manufacturer's specification
Check the control signal with an oscilloscope; on direct injection or diesel engines, leave this to a repair shop because of the high voltages
On diesels, check the per-cylinder injection corrections

Good to know

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

What each character of P2C28 means

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

Frequently asked questions

Can I keep driving with code P2C28?

Drive as little as possible and go to a repair shop. If you smell fuel or the engine is shaking badly, do not keep driving.

What causes code P2C28?

The most common causes are: alternator regulator drift - overvoltage; sense wire shorted to B+; connector pins corroded - high contact resistance.

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.