What Does P204E Mean?
The ECM is detecting unstable or erratic voltage signals from the reductant pressure sensor that fall outside expected parameters. This indicates intermittent connection issues, sensor degradation, or electrical interference.
Common Causes
35%
Loose or corroded sensor connector with intermittent contact
30%
Damaged wiring harness with intermittent opens or shorts
20%
Failing reductant pressure sensor with internal intermittent fault
10%
Poor ground connection causing voltage fluctuations
5%
Electromagnetic interference from nearby high-current components
Diagnostic Steps
1
Step 1: Thoroughly inspect sensor connector and clean terminals with electrical contact cleaner
2
Step 2: Perform wiggle test on wiring harness while monitoring live sensor data for dropouts or spikes
3
Step 3: Check wiring harness routing for proximity to high-voltage ignition components or damaged insulation
4
Step 4: Monitor sensor voltage over extended test drive including various operating conditions and road vibrations
5
Step 5: Replace sensor if wiring and connections are verified good but code persists
Estimated Repair Cost
$150 - $700
Parts + labor, varies by vehicle and location
The ECM is detecting unstable or erratic voltage signals from the reductant pressure sensor that fall outside expected parameters. This indicates intermittent connection issues, sensor degradation, or electrical interference.
The most common cause of P204E (Reductant Pressure Sensor Circuit Intermittent/Erratic) is: Loose or corroded sensor connector with intermittent contact
Typical repair costs for P204E range from $150 to $700, depending on the vehicle, location, and whether you do it yourself or go to a shop.
May cause intermittent power reduction or warning lights. Vehicle could enter limp mode unexpectedly during operation, creating potential driving hazard.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P204E to identify the root cause.
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Quick Info
Category
Powertrain
System
Selective Catalytic Reduction (SCR) Emissions System
Difficulty
Type
Generic (SAE)
Recommended Tools
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