Engine & fuel system
5 documented faults — symptoms, causes and workshop fixes.
Engine misfire
Water/oil ingress into spark plug orifice. Fix: clean and lubricate.
Overview
- Affects
- All models.
- Remedy
- Clean & lubricate
Symptoms
Engine malfunction indicator lamp (MIL) illuminated. Poor cold starting. Poor engine running.
Repair steps
- Clean ignition coil and spark plug orifice.
- Check spark plugs for insulator damage or arcing.
- Check cylinder head cover for leaks.
Data: Motorwise Workshop. Bulletin 3.
Failure to start
Overview
- Affects
- All models.
Symptoms
Failure to start when engine is hot. Trouble code stored in engine control module (ECM) fault memory.
Cause
Faulty crankshaft position (CKP) sensor.
Repair
- Replace crankshaft position (CKP) sensor.
- Access engine control module (ECM) fault memory and erase trouble codes.
Data: Motorwise Workshop. Bulletin 5.
Idle speed surges
Throttle valve not closing correctly due to build up of deposits in throttle body. Fix: clean and lubricate.
Overview
- Affects
- All models.
- Remedy
- Clean & lubricate
Symptoms
Engine jerking. Poor throttle response.
Repair steps
- Remove throttle body intake pipe.
- Clean deposits from inner wall.
- Actuate throttle valve manually 3 to 5 times.
- Inspect throttle body for any remaining contamination.
- If necessary clean again.
- Fit throttle body intake pipe.
- Check idle speed.
Data: Motorwise Workshop. Bulletin 6.
Engine malfunction indicator lamp (MIL) illuminated
Symptoms
Trouble codes stored: P0325, P1325.
Cause
Knock sensor (KS) fault.
Repair
- Check wiring connector and resistance of KS. Replace parts as necessary.
Data: Motorwise Workshop. Bulletin 7.
Knocking noise from engine compartment with engine idling
Overview
- Affects
- All models.
- Remedy
- Fit new part
- Parts
- 2 parts
Cause
Balancer shaft belt tensioner faulty.
Repair
- Fit new balancer shaft belt tensioner.
- Fit new balancer shaft belt.
Parts2 parts
| Part | Part number | Qty |
|---|---|---|
| Balancer shaft belt | 55221254 | 1 |
| Balancer shaft belt tensioner | 55221253 | 1 |
Data: Motorwise Workshop. Bulletin 8.
Brakes
1 documented fault — symptoms, causes and workshop fixes.
Squeaking noise from rear brakes
Cause
Handbrake cable sticking due to internal damage/corrosion.
Repair
- Replace both handbrake cables.
Data: Motorwise Workshop. Bulletin 4.
Body & trim
1 documented fault — symptoms, causes and workshop fixes.
Bonnet not opening or closing correctly
Cause
Bonnet catch seized.
Repair
- Clean and lubricate bonnet catch.
Data: Motorwise Workshop. Bulletin 1.
Wipers & visibility
1 documented fault — symptoms, causes and workshop fixes.
Noise from lower windscreen area
Overview
- Affects
- All models.
- Remedy
- Clean & lubricate
Cause
Dry contact surfaces on front suspension upper arm bushes.
Front suspension upper arm bushes worn.
Repair
- Check front suspension upper arm bushes for excessive play.
- Replace or lubricate front suspension upper arm bushes as necessary.
Data: Motorwise Workshop. Bulletin 2.
Glossary
Technical terms used in this guide.
- MIL
- Malfunction indicator lamp — the engine warning light on the dashboard
- ECM
- Engine control module — the electronic unit that manages the engine
- Trouble Codes
- Standardised fault codes stored by the engine control module, read with a diagnostic tool
- CKP
- Crankshaft position sensor — tells the engine control module where the crankshaft is in its rotation
- KS
- Knock sensor — listens for engine knock so the engine control module can retard the timing
- Control Module
- A control unit for one of the vehicle's systems (engine, gearbox, brakes, body, and so on)
- Crankshaft Position
- Where the crankshaft is in its rotation — used for ignition and injection timing
- Fault Memory
- The list of stored trouble codes in a control module
- Trouble Code
- A standardised fault code stored by a control module, read with a diagnostic tool
- Bushes
- Rubber mountings that let a suspension or body joint move without metal-to-metal contact
Frequently asked questions
What are the common faults with the Alfa Romeo 166 2.0?
This guide contains eight workshop bulletins for the Alfa Romeo 166 2.0. Of these, five concern the engine and fuel system and one the brakes. Symptoms, causes, repair steps and part numbers are shown where supplied.
Does every Alfa Romeo 166 2.0 have these faults?
No. These are patterns documented across the model by workshops, not predictions for an individual vehicle. Where a fault applies only to certain vehicles or VIN ranges, that is listed with the fault.
Can I check for Alfa Romeo 166 2.0 faults myself?
Many of them. The documented symptoms can be seen, heard or felt during a test drive.