Fault code lookup

PowertrainP0128

Caution

Severity: Caution - get it checked when you can

Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)

42 brands affected · Generic SAE J2012 description.

Key terms: SAE J2012: the standard generic code list · Powertrain: engine, transmission and emissions

Safety: This code relates to engine cooling or temperature. Overheating can damage the engine.

1What it means in plain English

The engine is not warming up as quickly as expected, which usually means the thermostat is stuck partly open.

2Common causes

  1. Stuck-open thermostat
  2. Low coolant level
  3. Faulty coolant temperature sensor
  4. Air pocket in the cooling system
  5. Damaged wiring or connector

3Can I drive?

Caution · drive with care

Have it checked soon: fuel economy, heater performance and emissions can suffer. If the engine overheats or the temperature gauge climbs, stop safely and let it cool.

This page gives general information. It is not professional advice. For a definite diagnosis and a repair quote, ask a qualified mechanic to inspect the car.

4Brand data 42

BrandCodeDescriptionSystem
Ashok Leyland CVP0128Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) SAEPowertrain
BAIC MotorP0128Thermostat fault BrandPowertrain
Mercedes-BenzP0128Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) SAEPowertrain
BMWP0128Thermostat jammed open BrandPowertrain
BYDP0128Coolant thermostat BrandPowertrain
CheryP0128Coolant thermostat BrandPowertrain
ChryslerP0128Thermostat plausibility BrandPowertrain
DaewooP0128Engine Coolant Temperature Sensor Circuit Malfunction BrandPowertrain
DaihatsuP0128Thermostat abnormal BrandPowertrain
DFFSP0128Thermostat fault BrandPowertrain
DFFXP0128Coolant thermostat BrandPowertrain
DFXKP0128Thermostat fault BrandPowertrain
EOBDP0128Termostat pendingin BrandPowertrain
FordP0128MIL ON DTC BrandPowertrain
GeelyP0128Coolant thermostat BrandPowertrain
GMP0128Engine Coolant Temperature(ECT) Below Thermostat Regulating Temperature BrandPowertrain
Great WallP0128Thermostat fault BrandPowertrain
HafeiP0128Coolant thermostat BrandPowertrain
HoldenP0128Engine Coolant Temperature (ECT) Below Thermostat Regulating Temperature BrandPowertrain
HondaP0128P1009, update BrandPowertrain
HyundaiP0128Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) SAEPowertrain
IsuzuP0128Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) SAEPowertrain
Land RoverP0128The coolant temperature is below the thermostat regulating temperature BrandPowertrain
MahindraP0128Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) SAEPowertrain
MaseratiP0128Thermostat rationality BrandPowertrain
MazdaP0128MIL ON DTC BrandPowertrain
MitsubishiP0128Coolant thermostat BrandPowertrain
OpelP0128Engine Coolant Temperature(ECT) Below Thermostat Regulating Temperature BrandPowertrain
PeroduaP0128Thermostat abnormal BrandPowertrain
PeugeotP0128Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) SAEPowertrain
PorscheP0128Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) SAEPowertrain
ProtonP0128Coolant thermostat BrandPowertrain
SaabP0128Engine Coolant Temperature(ECT) Below Thermostat Regulating Temperature BrandPowertrain
MG (SAIC)P0128Coolant Thermostat BrandPowertrain
SmartP0128Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) SAEPowertrain
SprinterP0128Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) SAEPowertrain
SubaruP0128Coolant Thermostat BrandPowertrain
SuzukiP0128Coolant thermostat (Coolant temperature below thermostat regulating temperature) BrandPowertrain
SWM MotorP0128Thermostat performance is unreasonable BrandPowertrain
TataP0128Thermostat Performance BrandPowertrain
ToyotaP0128Thermostat fault BrandPowertrain
VolkswagenP0128Coolant thermostat valve (N214): temperature below control range; No signal/communication BrandPowertrain

Legend: SAE is the generic J2012 description; Brand is text taken from that manufacturer’s data. Manufacturer rows keep the wording and language of the source data, and non-English text is tagged so screen readers pronounce it correctly.

5Extended variant codes 3

These 7-character codes are manufacturer-specific variants of P0128 and may be reported by some scan tools.

BrandCodeDescriptionSystem
HyundaiP012800No description available Powertrain
SsangYongP012800Thermostat (temperature below thermostat regulating temperature) BrandPowertrain
VolvoP012800If the DTC ECM- is set it shall be faulttraced before this DTC BrandPowertrain

6Related codes

  • P0120 Throttle/Pedal Position Sensor/Switch A Circuit
  • P0121 Throttle/Pedal Position Sensor/Switch A Circuit Range/Performance
  • P0122 Throttle/Pedal Position Sensor/Switch A Circuit Low Input
  • P0123 Throttle/Pedal Position Sensor/Switch A Circuit High Input
  • P0124 Throttle/Pedal Position Sensor/Switch A Circuit Intermittent
  • P0125 Insufficient Engine Coolant Temperature for Closed Loop Fuel Control
  • P0126 Insufficient Engine Coolant Temperature for Stable Operation
  • P0127 Intake Air Temperature Too High
  • P0129 Barometric Pressure Too Low
  • P012A Turbocharger/Supercharger Inlet Pressure Sensor Circuit
  • P012B Turbocharger/Supercharger Inlet Pressure Sensor Circuit Range/Performance
  • P012C Turbocharger/Supercharger Inlet Pressure Sensor Circuit Low

Browse Pxxx codes or P012xx codes.

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