Here the read-back line of the gas module supply relay carries voltage at a moment when it should not: the relay is commanded off, yet power is still present behind its contacts. A welded contact pair is the main suspect, followed by a sense wire touching another live circuit. The practical effect is a gas control module that never shuts down, so stored values may not be saved correctly and the battery drains while parked. The 2010 Saab V6 manual from GM Europe covers the engine relay counterpart P0690 within the same feedback test as P0689. P2A37 itself appears in no public manufacturer document. Ford's 2003 bi-fuel CNG pickups illustrate that the alternative fuel module is a separate box with its own relay outputs, which explains why J2012 gives it a relay code set of its own.
Medium severity. Can I keep driving?If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
Symptoms
- Check engine light, depending on calibration
- Battery drained after standing
- Relay clicks are missing at ignition off
Most likely causes
- Relay contacts welded closed
- Sense wire shorted to another live circuit
- Miswired retrofit gas installation feeding voltage back
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It affects emissions.
What each character of P2A37 means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- A: Hybrid or air and fuel
- 37: Specific fault in that system
Frequently asked questions
Can I keep driving with code P2A37?
If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
What causes code P2A37?
The most common causes are: relay contacts welded closed; sense wire shorted to another live circuit; miswired retrofit gas installation feeding voltage back.
Related codes
- P2A35AFCM Power Relay Sense Circuit
- P2A36AFCM Power Relay Sense Circuit Low
- P2A34AFCM Power Relay Control Circuit High
- P0690ECM/PCM Power Relay Sense Circuit High
Sources
- law.cornell.edu: 13 CCR 1968.2
- saabwisonline.com: dtc p0685 p0686 p0687 p0689 or p0690
- static.nhtsa.gov: INRD PE08063 33504P
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.