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Home / DTC / U0901 — Invalid Data from Ion Sense Module

U0901 — Invalid Data from Ion Sense Module

Detailed page for trouble code U0901.

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10,556generic
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U0901

Generic U — Network/User

Invalid Data from Ion Sense Module

Brand: Generic
Type: U — Network/User
Views: UK: 14 EN: 21 RU: 16
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Page language: EN

Causes

  • Faulty ion-sense module (internal failure or firmware error)
  • Corroded, loose, or damaged connector or wiring to the ion-sense module
  • Open, shorted, or high-resistance power supply or ground to the module
  • CAN or other vehicle network wiring fault (short to battery/ground, open, high resistance)
  • Electromagnetic interference or intermittent connection causing corrupted packets
  • Faulty ECM/PCM or gateway module interpreting data incorrectly

Symptoms

  • MIL (Check Engine Light) illuminated
  • Stored U0901 and possibly other network or sensor-related codes
  • Incorrect or missing ion-sense data displayed by scan tool (garbage values, out-of-range, or no response)
  • Driveability concerns if system depends on ion-sense input (misfire detection, ignition timing, rough idle)
  • Intermittent faults that may clear and return, or persist until repaired

What to check

  • Use a capable scan tool to read U0901 and any accompanying codes or freeze frame data
  • Attempt to communicate with the Ion Sense Module using manufacturer-specific functions; note if the module responds
  • Inspect the ion-sense module connector and wiring for corrosion, bent pins, heat damage, or water intrusion
  • Check battery voltage and verify stable supply voltage to the module with ignition on
  • Verify solid ground(s) at the module (measure continuity to chassis/negative battery)
  • Measure CAN (or other network) bus voltages and waveform quality with an oscilloscope if available (look for proper recessive and dominant levels and clean edges)

Signal parameters

  • Module supply voltage (key ON) — nominal battery voltage (~12V with engine off)
  • Module ground continuity to chassis/negative battery — low resistance
  • CAN High and CAN Low idle voltages — within manufacturer specification (look for expected recessive levels)
  • CAN bus differential waveform — clean dominant and recessive edges, correct bit timing if oscilloscope available
  • Presence and frequency of expected CAN messages/IDs from ion-sense module (seen with a scan tool or bus monitor)
  • Ion-sense signal amplitude/timing (if accessible) — within expected ranges for that sensor

Diagnostic algorithm

  1. Verify the code: Read freeze frame and stored codes; record module IDs and any related U or P codes.
  2. Check for network-wide issues: See if other modules report communication faults. If multiple nodes are affected, focus on CAN bus and battery/ground.
  3. Attempt to communicate: Use a scan tool to request data from the ion-sense module. Note whether it responds and if data values look plausible or corrupted.
  4. Visual inspection: Turn ignition off, disconnect battery if required by vehicle procedure, inspect connectors and wiring to the ion-sense module for damage, corrosion, water entry, or loose terminals.
  5. Power/ground tests: With ignition ON, measure supply voltage at the module connector and check key ground(s). Repair any open or high-resistance circuits.
  6. Communication line tests: With ignition ON, measure CAN High/Low voltages at the module. If readings are out of range or missing, trace wiring for short/open. Wiggle wiring while monitoring to find intermittent faults.
  7. Signal integrity: If available, use an oscilloscope or CAN bus analyzer to view message traffic and waveform quality. Look for missing packets, CRC errors, or noise.
  8. Isolate the module: If wiring and bus are good, disconnect the ion-sense module and check if related codes change or if bus behavior alters (follow manufacturer-safe isolation steps).
  9. Substitute or reflash: If possible, reflash/update module software per manufacturer guidance or substitute a known-good ion-sense module to confirm fault.
  10. Clear codes and road test: After repairs, clear codes and confirm the fault does not return under varied operating conditions.
  11. Safety note: Follow vehicle manufacturer procedures for handling battery, airbags, and SRS when disconnecting modules or performing repairs.

Likely causes

  • Connector contamination or bent pins at the ion-sense module
  • Intermittent CAN-H or CAN-L connection (loose splice, chafe, water ingress)
  • Low or missing module supply voltage or poor ground
  • Ion-sense module internal fault (most common if wiring and bus voltages are normal)
  • Recent repairs or aftermarket device installed on the vehicle network

Fault status

⚠️ Status
Invalid or corrupted data received from the Ion Sense Module — communication/data integrity error.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-3.0 hours

Similar codes

U0100 U0121 U0140 U0401 U0416
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