P2C26: Fuel Injector Group B Supply Sense Circuit

What it means

The ECM detects a generic fault on the supply sense circuit of fuel injector group B. Group supply voltage cannot be measured reliably.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test
• The engine or gearbox may go into limp mode

How it works

Fuel injector group B shares a supply feed, and the ECM monitors a sense circuit to check whether that feed can be measured reliably. P2C26 sets when the group B supply reading is unreliable, without identifying a definite low- or high-voltage condition.

Common causes

Most likely first.

1. Wiring or connector fault
2. Group supply fuse aged with high resistance

Symptoms

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

How to diagnose it

1. Use a scan tool to record freeze-frame data and compare group B injector supply readings with other available injector supply data.
2. With the ignition off, inspect group B injector connectors, the shared supply wiring and fuse for looseness, heat damage, corrosion or chafing.
3. Check the group B supply fuse and its terminals for excessive resistance or a poor connection, even if the fuse element is intact.
4. With the circuit energized as specified by the manufacturer, measure supply and sense-circuit voltage at the group B feed and compare the readings with the manufacturer's specification.
5. If the feed is sound, test continuity and shorts in the sense wiring and check whether the reading changes when the harness is moved.

Common fixes

• Clean and secure corroded or loose group B injector and fuse connections.
• Repair damaged group B supply or sense-circuit wiring.
• Replace a group B supply fuse or fuse-terminal assembly that has excessive resistance.
• Replace a failed injector-group supply sensing component only after wiring and feed tests isolate it.

Can I keep driving?

If the engine runs smoothly and the warning light is steady, limit driving and avoid heavy acceleration until the supply fault is diagnosed. A misfire, fuel smell, smoke or flashing warning light calls for stopping safely; continued driving can worsen engine damage and emissions.