U0691 code meaning
Lost Communication With Exhaust Pressure Sensor A
Network system Generic code U06xx codes Check engine light
What U0691 means
On Ford's 6.7 L and 3.0 L diesels of 2023, exhaust pressure sensor A measures pressure ahead of the turbine and is a SENT device. Ford's diesel OBD summary sets U0691 when the low-level SENT driver sees a communication error or no data within the expected window, when the line is held at one voltage level, or when the sensor reports an internal fault; the check runs continuously and needs 5 s. P0470 is kept for a SENT status error or a raw value above a limit. The same sensor has two plausibility tests: with the engine off it may differ from barometric pressure by no more than 15 kPa (P0471), and while driving it is compared against a model (P0474). Without this pressure, turbo and EGR control lose an input. U0692 covers sensor B.
U0691 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0691
- Check engine light
- Reduced boost or power on some engines
- EGR and turbo running on substitute values
Common causes of U0691
- Most likelySENT line shorted to ground or supply, or open, near the hot turbo
- PossibleSensor reports an internal error or stops sending
- PossibleConnector heat-damaged or corroded
- Less likelySensor damaged by soot or condensate in the pressure line
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Exhaust pressure sensor aVehicle bus wiring
What each part of U0691 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 91 | The exact fault in that area. |
What to do next
- Note U0691 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U0691
What does U0691 mean?
U0691 means "Lost Communication With Exhaust Pressure Sensor A". On Ford's 6.7 L and 3.0 L diesels of 2023, exhaust pressure sensor A measures pressure ahead of the turbine and is a SENT device. It is a generic code, so it means the same on every make.
Is it safe to drive with U0691?
Drive gently and only to a workshop. With U0691 the car can go into limp mode (reduced power) to protect itself.
Will U0691 fail an emissions test?
Yes, it can. U0691 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is U0691 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will U0691 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.