Besides driving the relay coil, a control module can read back the voltage behind the relay contacts to confirm that power actually arrives. P2A35 is the general fault of this feedback line for the relay that supplies the gas control module, without a statement about too low or too high. Typical are an open sense wire, a corroded pin or a blown fuse between contact and sense point. Roush CleanTech's propane manual for Ford trucks lists a missing supply, a blown fuse or lost power and ground of its alternative fuel module as reasons for losing it on the bus (U0108), which shows how supply problems surface there. No published calibration uses P2A35; the engine-relay sibling P0688 is the analogue. Electrical symptoms may be absent while the relay itself still works.
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
- Often no drivability change
- Occasional fallback to petrol if the supply really drops
Most likely causes
- Sense wire open or pin backed out
- Blown fuse between relay contact and sense point
- Corroded terminals in relay socket or module plug
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 P2A35 means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- A: Hybrid or air and fuel
- 35: Specific fault in that system
Frequently asked questions
Can I keep driving with code P2A35?
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 P2A35?
The most common causes are: sense wire open or pin backed out; blown fuse between relay contact and sense point; corroded terminals in relay socket or module plug.
Related codes
- P2A36AFCM Power Relay Sense Circuit Low
- P2A37AFCM Power Relay Sense Circuit High
- P2A32AFCM Power Relay Control Circuit/Open
- P0688ECM/PCM Power Relay Sense Circuit/Open
- U0108Lost Communication With Alternative Fuel Control Module
Sources
- law.cornell.edu: 13 CCR 1968.2
- roushcleantech.com: Roush CleanTech Diagnostics Manual DA 8.5.18
- 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.