OBD-I Codes List

GM 70 A/C Pressure Sensor Circuit High Pressure Indicated

Make
GM (1982-1995)
Category
Powertrain - Computer and Auxiliary Controls
Severity
Check Engine Light

How to read it

Code 70 reads as 7 flashes, pause, 0 flashes on the check-engine light. Jump terminals A and B on the ALDL connector with the key off, then turn the key on with the engine off and count the check-engine flashes.

New to flash codes? The How to Read GM OBD-I Codes with a Paperclip walks through the test and what the numbers mean. The general OBD-I guide covers the rest.

What does GM code 70 mean?

A/C Pressure Sensor Circuit High Pressure Indicated

Common causes of 70

  • Overcharged A/C system
  • Blocked condenser or failed cooling fan
  • Failed pressure sensor reading high
  • Air or moisture in the system

How to fix 70

  1. Read codes with an ALDL scan tool
  2. Compare sensor reading with manifold gauges
  3. Check the condenser for debris and the fan for operation
  4. Recover and weigh the charge if overfilled is suspected
  5. Replace the sensor if gauges read normal but signal reads high
  6. Clear the code and verify head pressure stays in range

Source

Qualified source review

Sources and review

Review: qualified. Read the source limits below.

  • GM OBD1 trouble codes, model and year page

    live reference page (troublecodes.net)

    Supports: code identity and GM meaning

    Fetched directly from the linked model page. Single publisher, so the record is qualified, not verified.

    https://www.troublecodes.net/GM/91_49B/

Last updated 2026-09-19.

Report a correction for 70. Include your vehicle, the issue and a source if you have one.

Related Powertrain - Computer and Auxiliary Controls Codes