P205C: Diesel exhaust fluid tank temperature sensor reading too low (circuit low)

Reductant tank temperature sensor circuit low

Severity: Severity not verified — if the car runs badly, have it inspected

The source read lists causes and symptoms but gives no driving-risk rating. On SCR trucks DEF faults can bring other SCR codes, so check what else is stored.

Source: how we rate severity

P205C in short

P205C means the temperature sensor in the diesel exhaust fluid tank is reporting a signal that is too low, usually a failed sensor or a short or open in its wiring. A SCR controller or software fault is less common. Ford has a bulletin for 2011-2015 Super Duty 6.7L diesels. Severity is not verified.

The DEF tank has a temperature sensor so the computer knows whether the fluid is frozen or warm enough to pump. If the sensor voltage falls below the range the maker expects, the computer stores P205C.

A low voltage points to a shorted or failed sensor or a wiring problem. Less often the SCR controller or its programming is at fault.

Ford has a bulletin for 2011-2015 Super Duty 6.7L diesels that lists P205C and P205D with P2043; the NHTSA summary does not say what the repair is.

Most likely causes

Cause 1: Failed DEF tank temperature sensor
Common general cause
Why it ranks here
PartsAvatar lists a failed sensor first, and its repair list begins with the sensor.
What would change this
Rises if the reading is stuck low or the sensor tests out of spec. Falls if the sensor reads normally.
Cause 2: Open or shorted circuit in the sensor wiring or connector
Common general cause
Why it ranks here
PartsAvatar lists open or shorted circuits in the sensor circuit as a cause.
What would change this
Rises if a wiring test finds a short to ground or a damaged connector. Falls if the wiring tests fine.
Cause 3: Condition covered by Ford TSB 18-2190 (6.7L Super Duty built on or before 9 Dec 2014)
Supported by vehicle data
Why it ranks here
Ford TSB 18-2190 lists P205C and P205D with P2043 on these trucks. The NHTSA summary does not say what the repair is, so only the coverage is known.
What would change this
Rises on a covered truck that also stores P2043. Falls on other vehicles.
Cause 4: SCR controller or engine computer fault or programming error
Possible — needs testing
Why it ranks here
PartsAvatar lists the controller or a programming error after the sensor and wiring.
What would change this
Rises only after the sensor and wiring pass.
How to test the engine control module (ecm / pcm)

What to test first

Start at step 1. Each result tells you what it means and where to go next.

Step 1: Read all stored codes and note whether other DEF or SCR codes are present, such as P2043 on a Ford 6.7L.
Low risk
- IfP2043 is also stored on a 2011-2015 Ford Super Duty 6.7L
  It meansAsk a dealer about TSB 18-2190.
  Points to: Condition covered by Ford TSB 18-2190 (6.7L Super Duty built on or before 9 Dec 2014)
- IfP205C is alone or with other sensor circuit codes
  It meansTest the sensor circuit.
  Go to step 2
Step 2: Read the tank temperature sensor on a scan tool, then measure the sensor and its wiring with a multimeter.
Best left to a shopTool: scan tool, multimeter
Warning:The DEF tank sits under the truck near hot exhaust parts, and DEF can irritate skin and eyes. Let a shop do the testing unless you are experienced.
- IfThe sensor reads stuck low or tests out of range
  It meansThe sensor is suspect.
  Points to: Failed DEF tank temperature sensor
- IfThe sensor tests fine but the wiring shows a short or open
  It meansThe wiring or connector is at fault.
  Points to: Open or shorted circuit in the sensor wiring or connector

Symptoms

Check engine light
Other SCR or diesel exhaust fluid codes stored

How to fix

Parts and cost context

Engine control module (ECM / PCM):Test the sensor and its wiring before suspecting the controller. Labour varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Ford

2011–2012 · F-250 Super Duty
Supported by vehicle data
Ford TSB 18-2190 lists P205C and P205D with P2043 on F-250 and F-350 with the 6.7L diesel built on or before 9 Dec 2014. Whether it is still current is not verified.
2011–2015 · F-450 Super Duty
Supported by vehicle data
Ford TSB 18-2190 also covers 2011-2015 F-450 and F-550 with the 6.7L diesel. Whether it is still current is not verified.

TSB 18-2190Status unverified
6.7L diesel MIL on with P2043, P205C and/or P205D
2011–2015f-250-super-duty, f-350-super-duty, f-450-super-duty, f-550-super-duty · issued September 10, 2018 · NHTSA 10144185
Applies to 6.7L diesel trucks built on or before 9 December 2014; the NHTSA summary says to follow the service procedure and does not name the repair.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

No curated relationships for P205C yet.

All Diesel emissions and glow plugs codes

Sources and review

P205C OBD trouble code: reductant tank temperature sensor circuit low — PartsAvatar
Ford TSB 18-2190: 6.7L diesel MIL on with P2043, P205C and/or P205D — Ford Motor Company / NHTSA , September 10, 2018

Last reviewed: October 16, 2026
Written by: Saurabh K.
Editorial review: Pending
Technician review: Technician review pending

This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error

Severity: Severity not verified — if the car runs badly, have it inspected

Most likely causes

Cause 1: Failed DEF tank temperature sensor

Cause 2: Open or shorted circuit in the sensor wiring or connector

Cause 3: Condition covered by Ford TSB 18-2190 (6.7L Super Duty built on or before 9 Dec 2014)

Cause 4: SCR controller or engine computer fault or programming error

What to test first

Step 1: Read all stored codes and note whether other DEF or SCR codes are present, such as P2043 on a Ford 6.7L.

Step 2: Read the tank temperature sensor on a scan tool, then measure the sensor and its wiring with a multimeter.