Peugeot 207 1.6 HDi 90bhp — Engine Thermostat Sticking Open
The engine coolant thermostat fails in the 'open' position. The engine never reaches its optimal operating temperature, killing fuel economy.
Severity
MinorDIY Difficulty
Moderate
Est. Cost
£100–£250
OBD Codes
P0128Cooling
Typical layout and location for the Cooling assembly.
Symptoms
- Temperature gauge drops when driving on the motorway
- Heater blows lukewarm air in winter
- MPG drops significantly
- Engine takes a very long time to warm up
Root Cause
The wax element inside the thermostat degrades, or the return spring weakens, preventing the valve from closing off coolant flow to the radiator.
How To Fix
- Scan for P0128 (Coolant Thermostat - Coolant Temp Below Regulating Temp).
- Replace the thermostat housing unit and gasket.
- Bleed the cooling system of air.
- Cost: £100-250
Estimated Repair Costs
| Repair Option | Est. Cost (GBP) |
|---|---|
| DIY (parts only) | £40–£100 |
| Independent Garage | £100–£250 |
| Main Dealership | £160–£400 |
Other Faults on This Variant
Timing Belt Failure (60,000 Mile Interval)
CriticalThe PSA 1.6 HDi engine has a 60,000-mile or 4-year timing belt interval — much shorter than most competitors. Belt failure destroys the engine. Many 207 owners are unaware of this critical maintenance item.
Injector Seal Leak (Chuffing / Black Death)
SevereCopper injector seals fail, allowing exhaust gases and unburnt diesel to escape and coat the top of the engine in a hard black tar affectionately known as 'Black Death'.
Turbo Oil Starvation and Destruction
CriticalThe 1.6 HDi (DV6) engine is infamous for destroying turbos. The cause is almost always oil sludge blocking the tiny gauze filter in the turbo oil feed pipe.
Disclaimer: Repair cost estimates are indicative and based on community data. Always get a quote from a qualified mechanic before proceeding with any repair.