P0182
PowertrainFuel Temperature Sensor A Circuit Low Input
This is usually a small job, not a big one. The fuel temperature sensor is feeding the ECU a voltage that's sat too low, often pinned near the bottom of its range, so the module thinks the fuel is hotter than it actually is. The sensor lives in or near the fuel system and tells the ECU how warm the fuel is so it can fine-tune the injection timing and quantity. Most of the time it's a cheap sensor or a corroded plug rather than anything dramatic in the engine itself.
ⓘ Information only. This page provides general educational information about fault code P0182. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P0182 mean?
P0182 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Fuel Temperature Sensor A Circuit Low Input.
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • Engine warning light on, frequently the only thing the driver notices
- • Slightly worse fuel economy, the sort you'd only spot over a few tankfuls
- • Rough idle or a stumble shortly after a cold start
- • Harder starting on cold mornings, occasionally needing a second crank
- • A faint flat spot under acceleration if the ECU is fuelling badly off the bad reading
Possible causes
Causes commonly associated with P0182, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Failed fuel temperature sensor, the most common cause. The internal thermistor goes low-resistance or shorts and the voltage drops with it
- 2. Corroded or loose connector at the sensor, very common on diesels where the plug gets dirty and damp
- 3. Wiring chafed through to ground somewhere in the harness, pulling the signal line low
- 4. Poor earth at the sensor or the ECU side, which skews the reading downward
- 5. Diesel or fuel contamination inside the connector causing a leakage path to ground
- 6. ECU software out of date on certain models, where a calibration update sorts a known reading fault
- 7. Failed ECU, rare and the last thing to suspect once everything else checks out
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. Read the live fuel temperature value on a scan tool first. If it's stuck reading very hot when the engine is stone cold, the signal is being pulled low and you've confirmed the fault is real
- 2. Unplug the sensor connector and inspect it for green corrosion, bent pins, or diesel seeping into the plug. A clean and reconnect fixes a fair few of these on the spot
- 3. Back-probe the signal wire with the connector plugged in and check the voltage. A healthy sensor swings roughly 0.5V cold up towards 4.5V hot; a reading flat near zero points to a short or a dead sensor
- 4. Disconnect the battery, then measure the sensor's resistance with a multimeter and compare against the manufacturer figure. Resistance falls as temperature rises, so a wildly low cold reading means a duff sensor
- 5. Check you've got a clean 5V reference and a solid ground at the connector. No reference or a poor earth will throw the same low-voltage code with a perfectly good sensor
- 6. Look up any service bulletins or software updates for your specific model before condemning hardware on the cars where that's a known fix
Common questions about P0182
How do I know if it's the sensor itself or just the wiring? +
Get a multimeter on it before you spend money. Measure the sensor's resistance cold and check it against the spec for your engine; if it reads near zero or won't change as it warms, the sensor is gone and a replacement sorts it. If the sensor measures correctly but you're still seeing the low voltage at the ECU, the fault is in the harness or the connector, usually corrosion or a wire chafed to ground. On diesels the connector itself is the usual villain, full of muck or fuel, so always pull the plug and look before condemning the part. A clean, a dab of dielectric grease and a reconnect clears a good number of these.
How long is this likely to take to put right? +
If it's just the sensor, a garage will usually have it done inside the hour once they've diagnosed it, assuming the sensor is in an accessible spot. Diagnosis itself eats most of the time, budget around half an hour to an hour of bench testing on top. Wiring repairs are the wildcard; tracing a short or a chafed wire through a loom can run to two or three hours depending on where the damage is and how buried the harness gets. Expect to pay roughly £40 to £120 for a sensor fitted at an independent, more if they have to chase a wiring fault.
Is a budget aftermarket sensor fine or should I pay for genuine? +
A decent branded aftermarket sensor from the likes of Bosch, Delphi or Febi is perfectly fine on most cars and costs a fraction of main dealer prices. These sensors are simple thermistors and a good aftermarket one will read just as accurately as the original. Steer clear of the unbranded £6 eBay specials though; cheap thermistors drift out of calibration and you can end up chasing the same code again a few months later. On a handful of newer models the ECU is fussy and prefers the genuine part, so if you've fitted a quality aftermarket one and it still throws the code, that's your hint to try OEM.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →