Fault code P0185 – a step-by-step guide to diagnosing and fixing it

The meaning of error code P0185 – Fuel Temperature Sensor B Circuit Malfunction

P0185: Causes, signs and repairs

Error code P0185 is displayed and the check engine light is on - what does this mean?

The OBD system detects a malfunction in the circuit of the fuel temperature sensor A. This DTC P0185 occurs when the control unit detects an implausible signal or an interruption in the sensor circuit. Specific variants of this error code can occur with some manufacturers such as BMW, Mercedes or Audi.

What causes can this error code have?

Defective fuel temperature sensor
Damaged wiring to the sensor
Corroded or loose plug connections
Short circuit in the sensor cable
Defective engine control unit
Interrupted ground connection
Dirty or clogged sensor
Defective fuel pump with integrated sensor

What symptoms occur in parallel with error code P0185?

Starting problems: The vehicle is difficult to start, especially in cold temperatures
Irregular idling: Engine runs unevenly or stutters when idling
Increased fuel consumption: Significantly higher consumption due to incorrect fuel mixture calculation
Loss of power: Reduced engine power during acceleration
Check engine light: Permanent display of the warning light in the dashboard
Jerking when driving: Uneven engine running while driving

How can the problem with error code P0185 be rectified?

The repair requires a systematic diagnosis of the fuel temperature sensor system.
Replace the fuel temperature sensor completely and clean the plug connection, then delete the fault memory and carry out a test drive
Check the wiring to the sensor, repair or replace damaged cables, check all connections for corrosion
Dismantle plug connections on sensor and control unit, clean with contact spray and refit securely
Use a multimeter to measure continuity and voltage, replace complete cable harnesses in the event of a short circuit
Localize and clean the ground connections of the sensor and set new ground points if necessary
Remove fuel pump module if sensor is integrated, replace and calibrate complete unit

FAQ - Frequently asked questions about DTC P0185

Can I continue driving with error code P0185?

It is possible to continue driving for a short time, but the fault should be rectified as soon as possible. The engine control unit works with substitute values, which leads to increased consumption and loss of power.

How much does it cost to repair error code P0185?

The costs vary between 150-800 euros depending on the cause. A simple sensor replacement costs around 150-300 euros, while a complete fuel pump replacement can cost up to 800 euros.

How do I recognize a defective fuel temperature sensor with P0185?

Typical signs are starting problems in cold temperatures, irregular idling and increased fuel consumption. An OBD diagnosis definitely confirms the trouble code.

Can I change the fuel temperature sensor for P0185 myself?

If the sensor is externally accessible, it is possible to replace it yourself. If the sensor is integrated in the fuel pump, specialists should carry out the repair.

How long does it take to repair EOBD code P0185?

A simple sensor replacement takes 1-2 hours. For more complex repairs to the fuel system, 4-6 hours may be required.

What consequential damage occurs if P0185 is ignored?

In the long term, engine damage can occur due to an incorrect fuel mixture. In addition, fuel consumption increases considerably and exhaust emissions deteriorate.

Vehicles in which error code P0185 occurs most frequently

Error code P0185 is a standardized OBD-II fault code for fuel temperature sensor problems and can occur in various vehicle manufacturers, but is most common in the following vehicles:

BMW: 3 Series E46, 5 Series E39, X3 E83, Z4 E85 (2000-2010)
Mercedes-Benz: C-Class W203, E-Class W211, ML W163, SLK R170 (1998-2008)
Audi: A4 B6/B7, A6 C5/C6, TT 8N, Q7 4L (2000-2012)
Volkswagen: Golf IV/V, Passat B5/B6, Touareg 7L, Sharan (1998-2010)
Ford: Focus MK1/MK2, Mondeo MK3, Galaxy, S-Max (2000-2012)
Opel: Astra G/H, Vectra B/C, Zafira A/B, Insignia (1998-2015)
Peugeot: 307, 407, 607, 807, Partner (2001-2012)
Renault: Laguna II/III, Espace IV, Scenic II, Megane II (2001-2010)

If the code P0185 occurs in your vehicle, you should first have a complete OBD diagnosis carried out. Many garages offer a free error code readout. As the fuel temperature sensor plays an important role in optimum engine control, it is advisable to have it repaired promptly to avoid consequential damage.

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