What it means
A fault has been detected in the cylinder 4 fuel heater control circuit. The code does not establish a particular engine type or heater purpose.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The engine control module monitors the control circuit for the fuel heater assigned to cylinder 4. This code sets when the circuit is detected as open, interrupting the electrical path to that heater.
Common causes
Most likely first.
- Open in heater or wiring
- Pin pushed back out of connector body
- Cracked solder joint inside the module or sensor
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
- Save the freeze-frame data and check whether the fault occurred during a cold start, when the cylinder 4 heater may be commanded on.
- Inspect the cylinder 4 heater wiring and connectors for damage, corrosion, loose fit, or a terminal pushed back into the connector.
- With the circuit safely powered down as specified by the manufacturer, check continuity through the cylinder 4 heater and its wiring to locate an open.
- Check connector pin fit and continuity across suspect connections, since a poor terminal or cracked internal solder joint can interrupt the circuit.
- If the heater and wiring pass, follow the manufacturer's procedure to assess the heater control module or sensor electronics for an internal open.
Common fixes
- Reconnect or repair a loose or damaged cylinder 4 heater connector.
- Repair an open or chafed section of cylinder 4 heater wiring.
- Replace the cylinder 4 fuel heater if its element is open.
- Repair or replace the faulty control module or sensor if an internal open is confirmed.
Can I keep driving?
If the engine runs normally, limited driving may be possible, but cold starts can become difficult and performance may suffer in cold weather. Avoid relying on the vehicle in conditions where a failed start would leave you stranded.
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.