Coil pack: faults, testing and replacing

What owners saw

• Lumpy idle or a misfire under load. One owner said a coil pack going down normally gives a misfire under load. Another said a misfire is shown by a fault code and the engine management light, though one owner with a misfire didn't get a light.
• Running on three cylinders. A Turbo owner driving to Silverstone found it ran on three and, after he switched the engine off and on, ran on four until he put load on it. The coil pack was dripping wet around the plug caps.
• Cutting out at traffic lights, or not holding revs when hot (2013). The garage suspected the coil pack. The advice was to unplug the air flow meter and see if it changes (Turbo only), to try a borrowed coil pack, and to look at a sticky EGR valve.
• Limp mode with P0300 and P0340 (2019, NA). One owner described P0300 as engine misfire detected, which could be several things, and P0340 as camshaft position, which is normally the coil pack on a Z22SE. See the 2019 case below and OBD fault codes.
• No start (2011, supercharged NA). The car stalled at a stop light, then cranked but wouldn't fire. The cause was not the coil pack. See the case below.

Water in the coil pack and plug wells

Water was the cause more often than anything else in these threads.

• A Turbo car left out in the rain without a cover had a coil pack wet around the plug caps. Drying it and spraying it with WD-40 helped, but it still missed under load, and a new pack fixed it.
• Another owner had a misfire after heavy rain that had been cured before by cleaning out the pack and plugs, and then came back.
• Things owners did: remove the pack and spray everything electrical with WD-40 or electrical contact cleaner (several suggestions); dry the spark plug holes (see Spark plug replacement); put the pack on a radiator or in an airing cupboard to be sure it is dry, which one owner said worked a treat and he never had the problem again; and strip the rubber boots off the bottom of the pack, push out the springs, and clean everything. One owner who did this found a varnish-like build-up of muck on the rubbers and rusty springs, and said it was all fine afterwards.
• The rubbers are replaceable. They just pull off the bottom of the pack. The pack itself is one piece. One owner was told by a garage that taking the coil pack off to change plugs could have dislodged corrosion and caused a misfire. That is the garage's theory, not a finding.
• Storage in damp conditions was blamed in 2019: both the plugs and the coil pack were corroded after a car sat for years without a garage.

Testing

• Check for spark. One owner suggested unbolting the coil pack and fitting spark plug testers (about £10 from Halfords) in the plugs, then turning the ignition on. If they light up, you have spark.
• Swap in a known good pack. Several owners said to borrow one from another NA, or to ask a dealer. An owner in Switzerland tried his pack on a friend's 2.2 Zafira and it worked, so it wasn't the pack. Another owner pointed out that the pack uses compression to detect the ignition sequence, so it is a glorified cam sensor, and might not work out of the car. That is one owner's point, and the Zafira test did show it working.
• Check the 12 V supply. In that no-start case the coil pack had 0 V on the brown/pink wire that powers it. The wiring diagram shows ignition power coming through the K18 relay, so the suggestion was a broken wire, a snapped connection on the relay or a faulty relay. In the end, a short to ground caused by the charge cooler relay wiring was the cause, probably from vibration. See Wiring diagrams.
• Check fuel and the cut-off. If it cranks but won't fire, listen for the fuel pump prime, press the fuel pump cut-off reset button (above the gearbox, bottom right in the engine bay, according to one owner), and check the fuses. One owner's car stopped because a boot fuse had worked loose. Another had a failing return valve in the fuel pump.
• Check the "loom of doom" connectors behind the header tank. Two owners said these are next to check if a fresh OEM coil pack doesn't cure P0300 and P0340.
• A diagnostic that wanted to change several parts. One owner said a dealer's answer to a misfire was to change the coil pack, then the air mass meter, then possibly the ECU. He bought a coil pack from Autovaux, fitted it himself and the problem was solved.

Aftermarket and cheap coil packs

• One owner said the Z22SE is very sensitive to cheap coil packs. Another said that P0340 has been reported with cheap aftermarket packs, and put it down to the aftermarket pack getting the ion sensing cam sensor emulation wrong. That is his explanation, not a confirmed one.
• The 2019 advice was to get an OEM pack. Even a used one at about £50 was said to be better than the aftermarket one that car had.
• How to tell a genuine one: one owner said there is a white sticker where the badge goes. Another owner's pack from a Vauxhall specialist, in a box with Vauxhall holograms, had no sticker, so the sticker is not proof either way.
• One owner said the Vauxhall part number for the NA unit appears to be 12580537, from the links in the thread. We haven't verified it.

A case that wasn't the coil pack (2019, NA)

An owner's car went into limp mode after the battery died in storage. Plugs and coil pack were corroded. A garage fitted a cheaper aftermarket coil pack and new plugs, and the code became P0340, so the cam sensor was replaced, then the crank sensor and an OEM coil pack, and the car had three coil packs in a week. The codes were still P0300 and P0340. In the end the cause was the ECU. He bought a second-hand Vectra ECU rather than pay £1.1k plus VAT from Vauxhall, and had a dealer reprogram it with TIS2Web and set the variant configuration with a Tech 2. The total, with a new coil pack, a timing chain and labour split across a specialist and a main dealer, was about £2k and took 3.5 months. This was one car. Don't assume your fault is the ECU, but it shows what to do when a fresh OEM pack doesn't cure these codes.

Removing and refitting

1. Turn the ignition off. Unplug the connector at the left-hand end of the cover: pinch the release clips hard until they click, then pull the plug towards the passenger side.
2. On the Turbo there is a plastic cover with "turbo" on it between the cam covers. Slide it about 25 mm towards the end the plug was on and lift it off (owners gave the direction differently, so check which way it moves).
3. Undo the Torx screws. Most owners said two. One said four bolts and one connector. Check what you have.
4. Lift the pack off the plugs. If you are lucky it comes free. One owner said that a damaged or overheated pack can weld itself to the top of a plug.
5. If you are changing the plugs, see Spark plug replacement. Owners said to put a touch of oil on the threads and start them by hand.
6. Refit in reverse. One owner asked whether fuse 8 needs to be pulled afterwards. Nobody answered.

Plugs: one owner said all plugs these days are preset, while another said they should still be checked against your car's setting. A Turbo owner suggested 0.7 mm. NGK iridium plugs are the most commonly used, according to one Turbo owner. A 2011 garage fitted VXR plugs (Bosch, part number 93187349), and the owner was told by another dealer that this was fine. Owners gave Vauxhall part numbers 91999038 for the 2.2 and 9195109 for a 2.0 (not VXR), with a standard plug costing £3.82 plus VAT each in 2011. For plugs on a boosted engine, see Misfire under boost: plugs, coils and sensors.

Buying one

• 2008 (Turbo): a Vauxhall dealer quoted £96.30 plus VAT for the coil "cassette". Another owner said to ring Autovaux, quote the part number 9198834 for the coil pack, and expect good prices.
• 2009: Autovaux quoted about £75 for a coil pack.
• 2011: Autovaux supplied a new Bosch pack for £84. A Vauxhall tech centre quoted £219 for a new coil pack and more plugs.
• 2013: an owner said he could get one £25 cheaper than his garage.

The air mass meter (Turbo only)

• The NA doesn't have an air mass meter, so don't chase one on a 2.2. Two owners said so.
• Part number 9201425 was given in 2008 for the Turbo air flow meter, with a dealer price of £117.90 plus VAT. Cheap eBay replacements were £28 to £34 (sensor only, not the housing).
• One owner said the sensor is the same part number on almost any Vauxhall and used one from a Corsa B to check his. Another tried a cheap eBay one and it misfired on all cylinders above 5% throttle and below 4,000 rpm, but ran fine above 4,000. Opinions on the cheap ones differed.
• An owner who bought one found the supplied tool didn't fit the VX220's screw head, because the security pin in the centre is larger than the bore in the tool. He suggested taking the whole assembly out and removing the screws from there.
• See MAF sensor faults.