What causes Ford code 34?

The EGR valve opening was not detected when the ECM commanded it. The EGR pressure transducer or its vacuum line failed. The EGR position or pressure feedback circuit is shorted to power. The ECM did not see the EGR valve open.

How do I fix Ford code 34?

Check the EGR valve and confirm it opens when the ECM commands it. Check the EGR pressure transducer and its vacuum line for a leak or a blockage. Check the EGR feedback circuit for a short to power. Test the EGR valve and pressure transducer and replace them only if they fail their own test. Test the ECM last, only after every circuit test has passed. Clear the code, then retest to confirm the EGR valve opening is detected.

Ford 34 EGR valve opening not detected or EGR pressure transducer fault

Q: What does Ford code 34 mean?

Ford code 34. EGR valve opening not detected or EGR pressure transducer fault.

Make: Ford (1981-1995)
Category: Powertrain - Auxiliary Emissions Controls
Severity: Check Engine Light

How to read it

Code 34 reads as 3 flashes, pause, 4 flashes on the check-engine light. Jumper the self-test input to signal return at the test connector, then run the key on engine off self test and the running self test, counting the check-engine flashes each time.

New to flash codes? The How to Read Ford EEC-IV Self-Test Codes walks through the test and what the numbers mean. The general OBD-I guide covers the rest.

What does Ford code 34 mean?

EGR valve opening not detected or EGR pressure transducer fault

Common causes of 34

The EGR valve opening was not detected when the ECM commanded it.
The EGR pressure transducer or its vacuum line failed.
The EGR position or pressure feedback circuit is shorted to power.
The ECM did not see the EGR valve open.

How to fix 34

Check the EGR valve and confirm it opens when the ECM commands it.
Check the EGR pressure transducer and its vacuum line for a leak or a blockage.
Check the EGR feedback circuit for a short to power.
Test the EGR valve and pressure transducer and replace them only if they fail their own test.
Test the ECM last, only after every circuit test has passed.
Clear the code, then retest to confirm the EGR valve opening is detected.

Source

Source review recorded

Sources and review

Review: checked against the recorded source material.

EEC-IV Ford trouble code table (MIL, description, type)
archived reference page (troublecodes.net via Wayback Machine)
Supports: code identity and meaning
Fetched directly. Code row matches the description used in the data file.
https://web.archive.org/web/20030720231430id_/http://www.troublecodes.net:80/Ford/eec-iv.shtml
Ford EEC-IV trouble codes, Crown Victoria, Mustang, Taurus, Thunderbird 1992-1995 (code, fault location, probable cause)
archived reference page (troublecodes.net via Wayback Machine)
Supports: code identity and probable causes
Independent table on the same archive site with matching code identity and additional probable causes.
https://web.archive.org/web/20160502051413id_/http://www.troublecodes.net:80/ford/crown-victoria-mustang-cobralxgt-taurus-thunderbird-1992-1995/
Ford EEC-IV trouble code table: code, fault location, probable cause (Crown Victoria, Mustang, Taurus, Thunderbird 1992-1995)
reference page (troublecodes.net)
Supports: per-code probable causes used for the page cause list and test order
Fetched 2026-09-30. The probable cause column is what the page lists, in source order, with the test order built from it.
https://www.troublecodes.net/ford/crown-victoria-mustang-cobralxgt-taurus-thunderbird-1992-1995/

Last updated 2026-10-10.

Report a correction for 34. Include your vehicle, the issue and a source if you have one.