Alfa Romeo1998–2001

166 2.5: Common faults & known problems

Common faults & known problems

9 known faults documented in workshop bulletins. Of these, three concern the engine and fuel system and one the brakes. Symptoms, causes, repair steps and part numbers are shown where supplied.

Technical specifications

Engine & fuel system

3 documented faults — symptoms, causes and workshop fixes.

Engine malfunction indicator lamp (MIL) illuminated

Overview

Affects: All models, →01/01.

Symptoms

Random/single misfire.

Cause

Intermittent connection at multi-plug between accelerator pedal position (APP) sensor and engine control module (ECM).

Repair

Check for diagnostic trouble codes and delete as necessary.
Remove multi-plug and join wires permanently by soldering.

Data: Motorwise Workshop. Bulletin 3.

Engine overheating at high vehicle speed

Affects All models.

Cause

Coolant pump impeller cracked.

Repair

Replace coolant pump.

Data: Motorwise Workshop. Bulletin 5.

Engine malfunction indicator lamp (MIL) illuminated

Affects All models with petrol engines.P0325P1325

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 9.

Brakes

1 documented fault — symptoms, causes and workshop fixes.

Squeaking noise from rear brakes

Affects All models.

Cause

Handbrake cable sticking due to internal damage/corrosion.

Repair

Replace both handbrake cables.

Data: Motorwise Workshop. Bulletin 8.

Suspension & drivetrain

1 documented fault — symptoms, causes and workshop fixes.

Poor response on uneven roads from rear suspension

Affects All models.

Cause

When driving in a sporty manner rear suspension can feel soft.

Repair

Fit suspension components, as used on 3.0 MT models.

Parts5 parts

Parts listed in the bulletin
Part	Part number	Qty
Front shock absorber	60662410	2
Front bump stop	60662611	2
Rear shock absorber	60662782	2
Rear bump stop	60662612	2
Nut	16112111	4

Data: Motorwise Workshop. Bulletin 2.

Clutch & gearbox

1 documented fault — symptoms, causes and workshop fixes.

Juddering when gently accelerating or cruising 60-70kph with AT torque converter lock-up clutch operating

Affects All models with automatic transmission (AT), except Euro stage 3 emissions.Fit modified part

Cause

leftHandAT torque converter lock-up clutch, closing point at 60 kph. rightHandAT torque converter lock-up clutch, closing point at 37 mph.

Repair

Fit modified TCM with higher lock-up speed.

Parts2 parts

Parts listed in the bulletin
Part	Part number	Qty
Transmission control module (TCM)	717.190.92	2,5
Transmission control module (TCM)	717.190.93	3,0

Data: Motorwise Workshop. Bulletin 1.

Air conditioning & heating

1 documented fault — symptoms, causes and workshop fixes.

Irregular operation of climate control

AC/heater air mix flap motor wiring trapped by engine bay fuse box/relay plate.

Overview

Affects: All models, →11/00

Symptoms

Fault 'air conditioning faulty, contact the Service Centre' displayed on digital multifunction display.

Repair steps

Check air mix flap motor wiring for damage.
If wiring insulation damaged, repair with tape.
Re-route wiring round left-hand end of fuse box/relay plate and secure to wiring harness clips.

Data: Motorwise Workshop. Bulletin 4.

Body & trim

1 documented fault — symptoms, causes and workshop fixes.

Bonnet not opening or closing correctly

Affects All models.Clean & lubricate

Cause

Bonnet catch seized.

Repair

Clean and lubricate bonnet catch.

Data: Motorwise Workshop. Bulletin 6.

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 7.

Glossary

Technical terms used in this guide.

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
KS: Knock sensor — listens for engine knock so the engine control module can retard the timing
TCM: Transmission control module — the electronic unit that manages the gearbox
AC/Heater: The heating and air-conditioning system
Accelerator Pedal Position: The sensor that tells the engine control module how far the accelerator is pressed
Control Module: A control unit for one of the vehicle's systems (engine, gearbox, brakes, body, and so on)
Multi-Plug: A multi-pin electrical connector on a wiring harness
Relay: An electrically operated switch
Wiring Harness: The bundled cables that carry power and signals around the vehicle
Bushes: Rubber mountings that let a suspension or body joint move without metal-to-metal contact
Misfire: One or more cylinders not firing correctly — the engine runs roughly or loses power

Frequently asked questions

What are the common faults with the Alfa Romeo 166 2.5?

This guide contains nine workshop bulletins for the Alfa Romeo 166 2.5. Of these, three 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 2.5 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 2.5 faults myself?

Many of them. The documented symptoms can be seen, heard or felt during a test drive.