P2A58

Code

Generic P — Powertrain

Alternative Fuel Vaporizer B Outlet Temperature Sensor Circuit High

Brand: Generic

Type: P — Powertrain

Views: UK: 18 EN: 39 RU: 25

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Page language: EN

Causes

Open or intermittent wiring in the sensor signal circuit (broken wire, poor splice)
Short to battery voltage in the sensor signal or reference circuit
Corroded, bent or pushed-out sensor connector pins
Failed temperature sensor (thermistor open or shifted characteristics)
Poor ground or reference voltage problem from the ECM
Heat damage to sensor or harness at the vaporizer outlet

Symptoms

Malfunction Indicator Lamp (MIL) or check engine light illuminated
Stored P2A58 diagnostic trouble code
Incorrect or implausibly high vaporizer outlet temperature shown in live data
Possible reduced system performance, limp-home fuel control or fuel-transfer restrictions (depending on vehicle strategy)
Alternate-fuel system operation abnormalities or refusal to switch fuels

What to check

Read freeze frame and full DTC list; note conditions when code set (engine temp, ambient, fuel selection)
Scan live data: confirm outlet temperature value and compare to expected
Visually inspect the vaporizer outlet sensor, harness and connectors for damage, corrosion or heat exposure
Wiggle-test harness while monitoring live data for intermittent changes
Backprobe the sensor connector with key ON, engine OFF to check signal voltage and reference voltage
Measure sensor resistance with connector disconnected and compare to vehicle-specific specification

Signal parameters

ECM reference supply: commonly 5 V reference (varies by manufacturer)
Normal sensor signal voltage range (generic): roughly 0.1–4.5 V under normal temperatures
Circuit high fault threshold (generic): signal voltage near supply (example >4.8 V) or open-circuit condition
Typical sensor type: thermistor (NTC or PTC) — resistance will change with temperature (example 10 kΩ at 25 °C is common but varies)
Expected resistance range: manufacturer-specific; check service literature for exact ohms vs temperature

Diagnostic algorithm

Capture freeze-frame and live data for the vaporizer B outlet temperature sensor while the code is active.
Perform a visual inspection of the sensor, connector and harness for heat damage, melting, corrosion or separation at the vaporizer outlet.
With ignition ON (engine OFF), backprobe the sensor connector: verify reference voltage (usually ~5 V) and check signal voltage. Note if signal is very high or at reference.
Disconnect the sensor and measure its resistance at ambient temperature. Compare measured resistance to the vehicle's specification or typical thermistor chart. An open or very high resistance indicates a bad sensor.
Check continuity between the sensor signal pin and the ECM pin; check for shorts to battery (+12 V) and to ground. Repair any chafed wires or shorts.
If wiring and sensor check good, inspect/verify ECM ground and connector pins for corrosion or damage. Repair as needed.

Likely causes

Open or damaged signal wire between sensor and ECM
Corroded/poor connector or terminal at the sensor
Faulty outlet temperature sensor
Short to battery voltage on the sensor signal or reference lead
Bad ground or intermittent ECM connector

Fault status

⚠️ Status

Alternative Fuel Vaporizer B outlet temperature sensor circuit high voltage — possible open circuit or short-to-voltage; inspect sensor, connector and wiring.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours