Alfa Romeo check engine light comes on to warn the driver that the On-Board Diagnostic System (OBD) has detected a problem. Check engine light may also be referred to as CEL or Malfunction Indication Lamp (MIL).
Alfa Romeo check engine can come on due to something as simple as a loose gas cap, but it can also indicate a problem with the engine, transmission, or EVAP system.
The check engine light in itself does not provide much information to help the driver know what is wrong. In this guide, we go over common problems that trigger Alfa Romeo's check engine light and troubleshoot the problem with an OBD-II scanner further.
Common symptoms that you notice when the Alfa Romeo light comes on:
- Engine running rough
- Check engine on or flashing.
- Engine juddering
- Lack of power
- Poor throttle response
- Unusual sound from the engine
- Smoke from the exhaust
- Limp home mode (emergency mode)
Any of these symptoms indicate that your Alfa Romeo is not running as it should.
Troubleshooting Alfa Rome Check Engine Light
To find out why your Alfa Romeo to check engine light is on, read the fault codes with an OBD-II scanner.
- Park your Alfa Romeo. Turn off the ignition and set the parking brakes.
- Locate the OBD-II port under the dashboard on the driver's side.
- Turn on the ignition but don't start the engine—press START without pressing the brake pedal.
- Allow the OBD-II scanner to power on and communicate with the vehicle.
- Select Read Code or Read Fault Codes depending on the scanner. Write down all the fault codes—research each code to find out about possible problems.
Reading the codes is a simple procedure that you can perform yourself. If you don't have an OBD-II scanner, your local auto parts store may let you borrow one free of charge.
Follow these steps to read Alfa Romeo check engine fault codes. These instructions work on any 1996 and newer Alfa Romeo, including Guilia, Mito, 159, 147, Stelvio, Brera, 156, Spider Giulietta, etc.
What triggers the check engine light on an Alfa Romeo?
Common problems that trigger the check engine light:
- Oxygen Sensor
- MAF Sensor
- Spark Plugs
- Catalytic Converter
- Loose gas cap
- Ignition Coil
- Vacuum Leak
- EVAP Leak
Also, the following problems affect mainly Alfa Romeo vehicles:
Variable Valve Timing (VVT): On Variable Valve Timing JTS gasoline engines, a check engine light accompanied by a lack of power, rough idle, and stalling can indicate a timing related problem. Some engines have tensioners not long enough to compensate for slack in the timing chain. As this can be a prelude to a much more dangerous timing failure, check this without delay. Code: P0016 (Cam-Crank Correlation)
Crankshaft Position Sensor: Many Alfa Romeo engines seem to have a more-than-average failure rate when it comes to a crankshaft position sensor. The most noticeable symptoms are an intermittent misfire, engine cutting out, or not starting occasionally. It can also cause various timing or alternator related codes. In most cases, the problem is very sporadic initially, but it happens more often as time goes by. Fault Code: P0335
Boost Issues: Turbocharged engines, both gasoline, and diesel are prone to various boost-related issues. This can be caused by various intake problems, such as broken hoses, a dirty air filter, or a blocked intercooler.
- Turbocharger: Another possibility is a worn turbocharger or stuck-open wastegate, resulting in a low boost. Lastly, the boost sensor can be defective, giving false readings. You might experience a lack of power and acceleration accompanied by whining or hissing noises from the engine area, smoke from the exhaust, and high fuel consumption. Related Code: P0235 - Turbocharger Boost Sensor
Pulse width modulation (PWM): All newer Alfas have pulse width modulation (PWM) controlled cooling fans, enabling continuous fan speed control. With time, a module in charge of this control can get damaged by moisture and corrosion, rendering cooling fans inoperable. Although this will not affect engine performance, it can still cause overheating. Code: P0480 related to cooling fan control.
Fuel Pressure: Diesel JTD engines use a common rail injection system, with fuel pressure controlled by an electronic regulator combined with a pressure sensor. If this doesn't operate properly, you might experience a loss of power, hard starting when cold and black smoke from the exhaust. In addition to the regulator with an integrated sensor, check the wiring and connector for damage. Code: P0091 (fuel pressure regulator)
Intake Swirl Flaps: Other quite common and potentially dangerous problems on JTD engines are intake swirl flaps. They control the intake geometry by opening and closing. With time, carbon buildup can obstruct the movement, sending the engine into limp mode. More importantly, flaps can even break off and fly into the engine, causing catastrophic damage. Code: P2009
Multiair Solenoid: Some Alfa Romeos Multiair engines, which utilize hydraulically actuated VVT systems to control intake valves' timing and duration. The most common failure point is a solenoid within the multi air unit coming loose. This causes rough idle and even a misfire on the affected cylinder. Related Code: P1061
Why is my Alfa Romeo Check Engine Light Flashing?
In some cases, the Alfa Romeo check engine may flash on and off. A flashing CEL is a clear and definite sign of engine misfire.
This can be caused either by faulty sparks, broken coils, or leaking fuel injectors.
It is not recommended to drive the vehicle if the check engine light is flashing. Whatever the cause, a misfire can quickly damage a catalytic converter and other engine components.