One owner in Italy had the fault on his 2.2 VX220 twice. The first time it went away after he opened the two connectors behind the expansion tank (the "loom of doom") and sprayed them with contact cleaner. The second time came the day after he washed the car: it wouldn't start, the scanner showed P1512 again, cleaning the same connectors and the throttle body connector didn't help, and the code came straight back when he erased it. Everything looked dry, apart from the area near the fuses under the front hood.
What P1512 means
One reading is "throttle min position not learned". The thread doesn't give a source for that, but the checks that follow all involve the throttle pedal, the throttle body or the engine computer's connections.
Things it has been linked to
- The blue connector behind the header tank making a bad connection (not corrosion, according to one owner). This is the loom of doom.
- The brown relay in the boot, K18, making a bad connection. One owner had P1512 once and says his was a dodgy connection on K18. In 2026 another owner found a contact that had come loose in its socket (see below). See relays and fuses for where it is: on the near side wheel arch in the boot, and the list there calls it the ECU relay.
- A broken sensor (the thread spells it "tamp sensor"), which would only make sense on a car that has one, and an NA doesn't.
- Wet ECU connectors, especially on an NA, because they see water from the engine cover.
What to check
Check these plugs: the throttle body plug, the ECU plugs, the black plug behind the header tank (the loom of doom), and the throttle pedal plug. On X3, the black plug, look especially at pins 1 to 6, which are all throttle pedal wires:
| Pin | Wire colour |
|---|---|
| 1 | Yellow |
| 2 | Green |
| 3 | Blue |
| 4 | Black |
| 5 | White |
| 6 | Brown |
The thread doesn't say which plug X3 is on the car, or show it.
Telling a wiring fault from a part fault
These tips come from a 2026 thread about a car that wouldn't start after refuelling.
- A fault that is always there and won't clear suggests a wiring problem, such as a short or a break.
- Graph the throttle body signals. If both tracks on the blade move smoothly and repeatably, that side may be fine. There could still be a problem with the two wires to the motor that drives the blade.
- Check the pedal too. Both of its tracks should rise and fall smoothly, without glitches.
- Ask which fault you have in the diagnostic tool, pedal or throttle. OpCom was used, and it can also try to drive the throttle body.
- Look for the other trouble codes. That car had P1512, P1515 and P1516 from a generic reader. The thread doesn't say what P1515 or P1516 mean. See the fault codes guide for reading codes.
- Two quick checks: the loom connector behind the header tank, and blown fuses.
A reset to try
One owner had P1512 after a host of faults caused by dirt in a connector, and says the answer was to turn the ignition on and not touch the throttle pedal for 30 seconds before starting. He adds "or maybe after, probably do both", so he isn't sure which. That is one owner's experience, not a documented procedure.
One owner's fix: several steps at once
On the second round he did several things at once, so we can't tell which one worked:
- Took down the rear wheel arch liner and cleaned the blue and grey connectors again.
- Changed all the fuses.
- Cleaned the relays under the front hood.
- Disconnected the battery for 15 minutes and "clicked the rearm button" (he doesn't say what that is).
The car started, but shut down after about 10 metres. The next morning the scanner showed a long list of faults (10 or 15). He cleared them and only P1516 came back. He then cleaned all the relays in the rear and swapped the fuel pump relay with the horn relay in the front hood, and P1516 went. He turned the car off and checked for faults four or five times, and none returned.
The thread doesn't say what P1516 means. The relays page lists the horn relay (K12) and the fuel pump relay (K16) as the same grey Bosch type, which is why they can be swapped for a test.
A third fix: a contact loose in the K18 socket (2026)
The car wouldn't start after refuelling, having been driven for about an hour, and was towed home. These are the steps the owner took, in order:
- Read P1512, P1515 and P1516 with a generic reader. After clearing, P1512 didn't come back immediately but returned when the ignition was switched off and on.
- Used OpCom to test the throttle body. It didn't move. The sensor voltages read 3.1 V and 1.9 V and didn't change during the test, though they changed when he moved the blade by hand. Pulling the plug sent them to 0 V and 5 V. A spare throttle body behaved the same, so he ruled out the throttle body. He asked whether 3.1 V and 1.9 V looked right with the throttle closed, and nobody answered.
- Checked the plugs, including the wheel arch connectors, the main engine plugs and the throttle body plug, and sprayed them with electrical spray. They looked fine. He ordered a new K18 relay, because he had read it often causes trouble.
- Measured at K18: +12 V at terminal 86 but none at terminal 30. By the wiring diagram, that points to a broken wire at that point, which he thought also feeds the fuel pump and the throttle body drive. A helper agreed it suggests a broken wire, and thought the big brown wire might run unbroken to the fuse at the front, though he wasn't sure whether it has joins or connectors on the way. He suggested rechecking at the terminals and, failing that, tracing from the relay forward, since terminal 86 has power so somewhere it has to join the larger wire.
- The cause: the "joint" is directly behind the relay socket. When he unplugged the sockets for easier access, he saw that one contact had come loose out of the socket. He pushed it back, switched the ignition on, waited 30 seconds and started the car straight away. He cleared the codes, and none came back. His photo isn't included here.
That is one report, posted on the day the thread was written, so there is no information on whether it lasted. The thread doesn't say whether the car is an NA or a Turbo. It also fits the earlier K18 reports, and the 30-second wait matches the reset above, though he doesn't say whether the wait mattered.