What it means
The cylinder 4 fuel heater has a performance fault: it is not operating as expected.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The cylinder 4 fuel heater warms fuel to support operation in cold conditions. The control module evaluates whether this heater performs as expected; this code indicates inadequate performance, which may come from the heater element, its wiring, or its control rather than identifying a specific failed part.
Common causes
Most likely first.
- Cylinder 4 fuel heater element worn or damaged
- Open or high resistance in heater wiring or connector
- Fault in the heater control module
- Poor electrical connection or ground
Symptoms
- Check engine light
- Fuel or powertrain warning light, if equipped
- Hard starting or rough running in cold weather
- Reduced engine performance in cold conditions
How to diagnose it
- Record freeze-frame data and note the ambient and engine conditions when the cylinder 4 heater performance fault appeared.
- Inspect the cylinder 4 heater element area, connector, wiring, and ground for damage, corrosion, or a loose connection.
- Use scan-tool data to check whether the module commands the cylinder 4 heater and whether its reported response changes as expected.
- Test the cylinder 4 heater element and its wiring for opens or excessive resistance, comparing results with the manufacturer's specification.
- If the element, wiring, connector, and ground pass, check the heater control module and its outputs against the manufacturer's specification.
Common fixes
- Restore a loose or poor ground or connector connection at the cylinder 4 fuel heater.
- Repair an open or high-resistance section of heater wiring.
- Replace the cylinder 4 fuel heater element if testing confirms it is worn or damaged.
- Repair or replace the heater control module if its output fails the specified checks.
Can I keep driving?
If the engine runs smoothly, short trips may be possible, but avoid cold-weather use if starting becomes difficult or running turns rough. Continued operation in cold conditions can bring reduced performance and increased emissions.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.