P2E80

Code

Generic P — Powertrain

A/C Compressor Control Module InternalTemperature Sensor B Circuit Intermittent/Erratic

Brand: Generic

Type: P — Powertrain

Views: UK: 18 EN: 33 RU: 21

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Loose, corroded, or damaged connector at the A/C compressor control module
Frayed, chafed, or shorted wiring in the sensor signal, reference, or ground circuit
Water intrusion or corrosion in the harness or connector
Intermittent internal failure of the temperature sensor (thermistor) inside the compressor module
Faulty A/C compressor control module electronics
Low or unstable battery/charging system voltage or poor ground

Symptoms

Intermittent A/C cooling or sporadic compressor engagement
HVAC temperature fluctuates or does not match set temperature
MIL/check-engine lamp or A/C-related warning illuminate
Stored or pending DTC P2E80 (or similar) in scan tool
Compressor cycles on/off unexpectedly or runs continuously in some conditions

What to check

Read and record all stored/pending codes and freeze-frame data with a scan tool; note when the code sets
Visually inspect wiring and connectors at the compressor for corrosion, damage, pin push-out, or water intrusion
Wiggle test wiring harness and connectors while monitoring live sensor data to try to reproduce the intermittent behavior
Backprobe sensor signal, reference (usually 5V or ignition-switched reference), and ground with key ON and monitor voltages
Measure continuity and resistance between the compressor module connector and the PCM/ECU where applicable
Check vehicle battery/charging system voltage and engine chassis ground integrity

Signal parameters

Sensor type: typically an NTC thermistor (resistance changes with temperature)
Reference voltage: commonly a stable 5 V reference from the module or PCM (verify for vehicle)
Expected signal voltage: normally varies with temperature within a 0.5–4.5 V range (vehicle-specific)
Open-circuit condition: signal voltage near battery voltage or near 0 V (depending on circuit design) or very high resistance (> tens to hundreds of kΩ)
Short-to-ground/short-to-VB conditions will drive the signal to near 0 V or near battery voltage respectively
Intermittent fault: signal will rapidly jump or drop, show noisy/unstable waveform, or drop in/out intermittently

Diagnostic algorithm

Connect a capable scan tool and confirm P2E80 is present; record freeze-frame and live data for the internal temperature B signal while cycling HVAC and compressor states.
Visually inspect the compressor control module connector and harness for damage, corrosion, moisture, or rodent chew. Repair or replace any damaged sections.
With connector seated, backprobe the signal, reference, and ground pins. With ignition ON (engine off if required), verify reference voltage (≈5V), stable ground, and that the signal voltage responds to ambient temperature or changes smoothly.
Perform a wiggle test on the harness and connector while monitoring live data to try to reproduce the intermittent/erratic signal. Inspect any areas where wires pass through body panels or near moving parts.
If intermittent persists, disconnect the compressor module and measure the internal sensor resistance at the module connector across the sensor terminals (compare to vehicle-specific temperature/resistance chart if available).
Check continuity from the connector to the PCM or HVAC control module on signal and ground circuits; repair any opens or high-resistance connections.
Verify stable supply voltage to the compressor control module under load; inspect and clean ground points. Repair as needed.
If wiring and connectors check good but the intermittent fault remains and sensor resistance/response is out of spec or inconsistent, consider replacement of the A/C compressor control module (or internal sensor assembly) per service manual.
After repairs, clear codes, perform the required A/C system relearn or initialization (if applicable), then road-test and monitor live data to confirm the fault does not return.
Safety note: avoid damaging refrigerant lines when accessing the compressor. Follow vehicle-specific service procedures for removing/replacing the compressor module.

Likely causes

Corroded or loose connector at the compressor control module
Damaged wiring harness near condenser, compressor, or routing points
Intermittent internal sensor element failure in the compressor module
Poor ground or intermittent supply voltage to the compressor control module
Failed compressor control module

Fault status

⚠️ Status

Intermittent/erratic signal detected from A/C compressor control module internal temperature sensor B circuit. Signal fluctuates or is dropping in/out beyond allowed thresholds.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.5-3.0 hours