OBD-II Diagnostic Trouble Code
P2046 — Reductant Temperature Sensor Circuit Intermittent
P2046 means the reductant (DEF) temperature sensor signal is dropping out or jumping intermittently. The ECM saw sudden changes that cannot be real temperature changes. This usually points to a loose connection or chafed wire, though a failing sensor can do it too.
Severity 2/5
Truck-relevant
Service soon
Severity
Service soon
Reductant Temperature Sensor Circuit Intermittent
Code
P2046
Category
Powertrain
Subsystem
Aftertreatment
Truck-relevant
Yes
What this means for truckers
Service this week on a Cummins X15, Detroit DD15, PACCAR MX-13. Not an immediate stop, but ignoring it usually leads to a more expensive fix downstream.
Before you replace parts — try this first
P2046 on the Aftertreatment system is most often loose or corroded def sensor connector — not a dead part. On commercial diesels especially, work these in order before spending money on parts:
- Confirm the symptoms. Match what your truck is doing to the Symptoms section below. If the code is set but the symptoms are not there, clear the code and re-test after a drive cycle — it may not return.
- Clean and dry the sensor connector. Water, road salt, or oil seeping into a connector is the #1 fake sensor failure. Disconnect, look for green corrosion or moisture, spray with electrical contact cleaner, dry, reseat. Many faults clear here for $0.
- Inspect the wiring harness. Trace the wire from the sensor toward the ECM — look for chafing against the engine block, melted insulation near the turbo or exhaust, or pinch points where a clamp has rubbed through.
- Test the sensor before swapping it. Most Common Causes (below) list the expected voltage or resistance range — a $20 multimeter saves a $300 sensor swap that does not fix the problem.
- Only then, replace the part. Use the OEM or a tier-1 aftermarket. Cheap sensors throw the same code in two weeks.
Symptoms
DEF warning and check-engine light that may come and go, sometimes with a derate countdown that starts and stops. DEF heating and dosing may be interrupted while the fault is active.
Common causes
- CommonLoose or corroded DEF sensor connector ($80–$300)
- CommonHarness chafed or partly broken near the tank or frame rail ($100–$400)
- OccasionalFailing sensor inside the tank header or supply module ($700–$2000)
- RarePoor ground for the aftertreatment module ($100–$300)
How to fix
Wiggle-test the connector and harness while watching DEF temperature live
When to use: First step to find the intermittent spot
Clean the connector, check terminal tension and reseal
When to use: When the reading jumps with connector movement
Repair any chafed wiring and re-clip the harness
When to use: When the fault follows harness movement away from the connector
Replace the tank header or supply module assembly
When to use: When wiring is good but the reading still jumps
Affects most
No specific vehicle pattern found in our complaint database. This code can appear on any vehicle that supports OBD-II diagnostics.
Related
- → Browse all DTC trouble codes
- → Decode a VIN to check codes for your truck
- → Owner-operator maintenance guides
- → P2002 — Diesel Particulate Filter Efficiency Below Threshold (Bank 1)
- → P2003 — Diesel Particulate Filter Efficiency Below Threshold (Bank 2)
- → P2031 — Exhaust Gas Temperature Sensor Bank 1 Sensor 2
- → P2032 — Exhaust Gas Temperature Sensor Bank 1 Sensor 2 Low
- → P2033 — Exhaust Gas Temperature Sensor Bank 1 Sensor 2 High
Frequently Asked Questions
Can I drive with code P2046?
P2046 is severity 2 — service this week. Not an immediate stop, but ignoring it usually compounds the problem. Most common cause for this code is a worn sensor or minor performance fault that won't strand you today but will get more expensive the longer you wait.
How much does it cost to fix P2046 on a commercial truck?
Total repair cost ranges $80–$2000 depending on the root cause. The cheapest fix is usually the first one listed below — Loose or corroded DEF sensor connector — which is also the most common. On commercial trucks the cost is usually higher than passenger vehicles due to part availability and shop labor rates ($120–185/hour at most truck shops, vs $90–130 at general auto shops). DIY-capable fixes (sensors, hoses, filters) are at the low end; major component replacements (turbo actuator, high-pressure fuel pump, transmission solenoid pack) are at the high end. Always diagnose with a scan tool BEFORE replacing parts — guessing wrong on a $1,500 turbo actuator when the actual issue was a $30 boost hose is a common expensive mistake.
Will P2046 fail a DOT inspection?
Yes — P2046 is an emissions-related code, and DOT inspectors check emissions compliance. An active emissions code with a check engine light can result in an out-of-service violation under FMCSA Part 393. The truck typically can't be moved until the code is cleared. Repeated emissions violations escalate to CSA scores.
What's the difference between P2046 and related codes?
P2046 is closely related to: P2002 (Diesel Particulate Filter Efficiency Below Threshold (Bank 1)), P2003 (Diesel Particulate Filter Efficiency Below Threshold (Bank 2)), P2031 (Exhaust Gas Temperature Sensor Bank 1 Sensor 2), P2032 (Exhaust Gas Temperature Sensor Bank 1 Sensor 2 Low). These codes share the same subsystem (aftertreatment) and often appear together. If you see this code, scan for the full code list — fixing the root cause usually clears multiple companion codes at once. If only P2046 is set without the companions, the issue is more isolated.
How do I prevent P2046 from coming back after a repair?
For P2046 (Reductant Temperature Sensor Circuit Intermittent), prevention centers on the aftertreatment system. Run quality DEF (verify supplier — BlueDEF, PEAK, Yara Air1). Don't skip parked regens — when the dash asks for one, do it. Avoid extended idle time which fouls the DPF. Replace NOx sensors at the OEM interval (typically 400K miles).