P2E7F: A/C Compressor Control Module Internal Temperature Sensor B Circuit Low

What it means

The ECM detects a circuit low fault on the a/c compressor control module internal temperature sensor b circuit. Reading cannot be used reliably for control.

At a glance

• Usually lights the check-engine light
• The engine or gearbox may go into limp mode

How it works

Internal temperature sensor B monitors temperature inside the A/C compressor control module. The ECM monitors its circuit voltage; this code sets when the signal falls below the expected range, commonly from a signal short to ground or an internally shorted sensor.

Common causes

Most likely first.

1. Signal wire shorted to ground
2. Internal sensor short
3. Connector pins corroded - high contact resistance

Symptoms

• Check-engine light may be on
• Air conditioning may be reduced or disabled

How to diagnose it

1. Use a scan tool to save freeze-frame data and check whether sensor B's reported temperature is implausibly low or fixed.
2. Inspect the compressor control module connector and sensor B wiring for damage, corrosion, moisture, or a signal wire contacting ground.
3. Check live data during compressor operation to see whether sensor B's reading responds plausibly or stays low.
4. Using the manufacturer's wiring diagram, test the sensor B signal circuit for a short to ground and inspect connector pin contact.
5. If the circuit passes, test sensor B against the manufacturer's specification for an internal short or failed response.

Common fixes

• Clean and secure corroded or loose sensor B connector contacts where serviceable.
• Repair a sensor B signal wire shorted to ground or damaged harness section.
• Replace sensor B if it fails the manufacturer's checks.

Can I keep driving?

The A/C may be limited or disabled because the compressor control module cannot trust sensor B's reading. Driving is generally possible if the vehicle otherwise operates normally, but stop if an overheating warning appears.